0000950170-24-025935 | 10-K | XBRL Viewer | Cyclerion Therapeutics INC

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Summary of Significant Accounting Policies - Income Taxes (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Accounting Policies [Abstract]
Income tax, penalties and interest accrued	$ 0	$ 0

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Preferred Stock	Paid in capital	Accumulated deflicit	Accumulated other comprehensive loss
Beginning balance at Dec. 31, 2021	$ 48,246			$ 263,345	$ (215,076)	$ (23)
Beginning balance (in shares) at Dec. 31, 2021		2,170,509
Net loss	(44,078)				(44,078)
Issuance of common stock upon exercise of stock options, RSUs and employee stock purchase plan	29			29
Issuance of common stock upon exercise of stock options, RSUs and employee stock purchase plan (in shares)		5,427
Share-based compensation expense related to issuance of stock options and RSUs to employees and employee stock purchase plan	5,091			5,091
Share-based compensation expense related to issuance of stock options to non-employees	1,161			1,161
Foreign currency translation adjustment gain	3					3
Ending balance at Dec. 31, 2022	$ 10,452			269,626	(259,154)	(20)
Ending balance (in shares) at Dec. 31, 2022	2,175,936	2,175,936
Net loss	$ (5,263)				(5,263)
Issuance of common stock	1,953			1,953
Issuance of common stock (in shares)		225,000
Issuance of preferred stock value	3,047			3,047
Issuance of preferred stock ( in shares)			351,037
Issuance of common stock upon exercise of stock options, RSUs and employee stock purchase plan	24			24
Issuance of common stock upon exercise of stock options, RSUs and employee stock purchase plan (in shares)		44,227
Vesting of restricted stock awards (in shares)		29,063
Share-based compensation expense related to issuance of stock options and RSUs to employees and employee stock purchase plan	1,042			1,042
Share-based compensation expense related to issuance of stock options to non-employees	25			25
Foreign currency translation adjustment gain	8					8
Fractional shares issuance (in shares)		(67)
Ending balance at Dec. 31, 2023	$ 11,288			$ 275,717	$ (264,417)	$ (12)
Ending balance (in shares) at Dec. 31, 2023	2,474,159	2,474,159	351,037

Commitments and Contingencies	12 Months Ended
Dec. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	8. Commitments and Contingencies Other Funding Commitments In the normal course of business, the Company enters into contracts with clinical research organizations and other third parties for clinical and preclinical research studies and other services and products for operating purposes. These contracts are generally cancellable, with notice, at the Company’s option and do not have any significant cancellation penalties. Guarantees On September 6, 2018, Cyclerion was incorporated in Massachusetts and its officers and directors are indemnified for certain events or occurrences while they are serving in such capacity. The Company enters into certain agreements with other parties in the ordinary course of business that contain indemnification provisions. These typically include agreements with directors and officers, business partners, contractors, clinical sites and customers. Under these provisions, the Company generally indemnifies and holds harmless the indemnified party for losses suffered or incurred by the indemnified party as a result of the Company’s activities. These indemnification provisions generally survive termination of the underlying agreements. The maximum potential amount of future payments the Company could be required to make under these indemnification provisions is unlimited. However, to date the Company has not incurred material costs to defend lawsuits or settle claims related to these indemnification provisions. As a result, the estimated fair value of these obligations is minimal. Accordingly, the Company did not have any liabilities recorded for these obligations as of December 31, 2023 or December 31, 2022. Separation Benefits As part of the separation benefit of former Chief Financial Officer, the Company shall pay to former Chief Financial Officer a payment of $0.1 million on each of the six-month and nine-month anniversaries of November 15, 2023, in the event the former Chief Financial Officer has not secured full-time employment prior to the anniversary date.

Commitments and Contingencies

12 Months Ended

Dec. 31, 2023

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

8. Commitments and Contingencies

Other Funding Commitments

In the normal course of business, the Company enters into contracts with clinical research organizations and other third parties for clinical and preclinical research studies and other services and products for operating purposes. These contracts are generally cancellable, with notice, at the Company’s option and do not have any significant cancellation penalties.

Guarantees

On September 6, 2018, Cyclerion was incorporated in Massachusetts and its officers and directors are indemnified for certain events or occurrences while they are serving in such capacity.

The Company enters into certain agreements with other parties in the ordinary course of business that contain indemnification provisions. These typically include agreements with directors and officers, business partners, contractors, clinical sites and customers. Under these provisions, the Company generally indemnifies and holds harmless the indemnified party for losses suffered or incurred by the indemnified party as a result of the Company’s activities. These indemnification provisions generally survive termination of the underlying agreements. The maximum potential amount of future payments the Company could be required to make under these indemnification provisions is unlimited. However, to date the Company has not incurred material costs to defend lawsuits or settle claims related to these indemnification provisions. As a result, the estimated fair value of these obligations is minimal. Accordingly, the Company did not have any liabilities recorded for these obligations as of December 31, 2023 or December 31, 2022.

Separation Benefits

As part of the separation benefit of former Chief Financial Officer, the Company shall pay to former Chief Financial Officer a payment of $0.1 million on each of the six-month and nine-month anniversaries of November 15, 2023, in the event the former Chief Financial Officer has not secured full-time employment prior to the anniversary date.

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2023

Income Tax Disclosure [Abstract]

Summary of reconciliation of income taxes computed using the U.S. federal statutory rate

A reconciliation of income taxes computed using the U.S. federal statutory rate to that reflected in operations follows (in thousands):


	Year Ended December 31,
	2023			2022
U.S.	$	(5,181	)	$	(44,063	)
International		(82	)		(15	)
Loss before benefit from income taxes	$	(5,263	)	$	(44,078	)
Income tax benefit using U.S. federal statutory rate	$	(1,105	)	$	(9,256	)
State income taxes, net of federal benefit		(5	)		(2,693	)
Non-deductible share-based compensation		(9	)		266
Share-based compensation - shortfalls/(windfalls)		1,196			833
Permanent differences		1			14
Tax credits		(500	)		(1,652	)
Other		17			3
Change in valuation allowance		405			12,485
	$	—		$	—

Summary of deferred tax assets (liabilities)

Deferred tax assets (liabilities) consist of the following as of December 31, 2023 and 2022 (in thousands):


	Year Ended December 31,
	2023			2022
Deferred tax assets:
Net operating loss carryforwards	$	48,535		$	47,079
Tax credit carryforwards		10,388			9,848
Share-based compensation		7,071			8,354
Property and equipment		—			1
Capitalized research and development		16,440			17,399
Accruals and reserves		2			340
Total deferred tax assets	$	82,436		$	83,021

Deferred tax liabilities:
Operating lease - right of use asset	$	—		$	(333	)
Prepaid sublease termination		—			(658	)
Total deferred tax liabilities		—			(991	)
Net deferred tax assets		82,436			82,030

Valuation allowance		(82,436	)		(82,030	)
Net deferred tax assets	$	—		$	—

Loss per share - Schedule of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Numerator:
Net loss from continuing operations	$ (12,593)	$ (18,246)
Net gain (loss) from discontinued operations	7,330	(25,832)
Net loss	$ (5,263)	$ (44,078)
Denominator:
Weighted average shares used in calculating net gain (loss) per share - basic	2,338	2,173
Weighted average shares used in calculating net gain (loss) per share - diluted	2,338	2,173
Net gain (loss) per share - basic and diluted
Net loss per share from continuing operations, basic	$ (5.39)	$ (8.4)
Net loss per share from continuing operations, diluted	(5.39)	(8.4)
Net gain (loss) per share from discontinued operations, baisc	3.14	(11.89)
Net gain (loss) per share from discontinued operations, diluted	3.14	(11.89)
Basic net loss per share	(2.25)	(20.28)
Diluted net loss per share	$ (2.25)	$ (20.28)

Discontinued Operations - Schedule of transaction consideration received from the sale of the Transferred Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Disposal Group, Including Discontinued Operation, Classified Balance Sheet Disclosures [Abstract]
Closing payment	$ 8,000
Expense reimbursement	2,402
Investment in Tisento Parent	5,350
Gross transaction consideration from the sale	15,752	$ 0
Net assets sold	0
Gain on disposal of discontinued operations	$ 15,752

Leases - Sublease as Lessor (Details) $ in Millions	12 Months Ended
Leases - Sublease as Lessor (Details) $ in Millions	Dec. 31, 2023 USD ($)	Dec. 31, 2020 USD ($)	Sep. 15, 2020 ft²
Sublease as lessor
Rentable space terminated from lease agreement (in square feet) \| ft²			15,700
Sublease termination agreement estimated fair value of rooms		$ 1.5
Sublease termination agreement estimated fair value of services		$ 2.9
Prepaid rooms balance reclassified from other assets	$ 1.4
Term of lease	8 years 10 months 17 days

Share-based Compensation Plans - Stock Awards Containing Market Conditions (Details) - $ / shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Number of Options
Granted (in shares)	0	0
Outstanding at end of the year (in shares)	7,500
Weighted-Average Exercise Price
Outstanding at end of the year (in dollars per share)	$ 40.2
Assumptions used to estimate fair value of performance-based stock options
Weighted average risk-free interest rate	3.47%	1.93%
Expected dividend yield	0.00%	0.00%
Expected stock price volatility	93.19%	98.90%
Market-based Stock Options
Number of Options
Outstanding at beginning of the year (in shares)	15,000
Cancelled or forfeited (in shares)	(7,500)
Outstanding at end of the year (in shares)	7,500	15,000
Weighted-Average Exercise Price
Outstanding at beginning of the year (in dollars per share)	$ 40.2
Cancelled or forfeited (in dollars per share)	40.2
Outstanding at end of the year (in dollars per share)	$ 40.2	$ 40.2
Weighted Average Remaining Contractual Term (years)
Weighted average remaining contractual term, outstanding at the end of period (in years)	5 years 10 months 24 days
Weighted Average Remaining Contractual Term, Exercisable (in years)		6 years 10 months 24 days
Weighted Average Remaining Contractual Term, Cancelled or forfeited	5 years 10 months 24 days

Summary of Significant Accounting Policies - Leases (Details) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($)
Leases
Election of practical expedients package	true
Impairment of ROU asset	$ 3.3

Income Taxes - Additional disclosures (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Income Taxes
Deferred tax assets, valuation allowance	$ 405,000	$ 12,485,000
Tax credit carryforwards	10,800,000	10,200,000
Provision for income tax	0	0
Unrecognized tax benefits	0	0
Accrued interest or penalties	0	0
Federal
Income Taxes
Net operating loss carryforwards	$ 177,000,000	172,000,000
Income tax credit expiration description	Federal credits begin to expire in 2040 and will continue to expire through 2041. State credits begin to expire in 2022 and continue through 2034
State
Income Taxes
Net operating loss carryforwards	$ 178,000,000	$ 173,000,000
Income tax credit expiration description	begin to expire in 2040 and will continue to expire through 2042

Share-based Compensation Plans - Summary of RSA activity (Details) - Restricted Stock Awards	12 Months Ended
	Dec. 31, 2023 $ / shares shares
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Unvested at the beginning of the period (in shares) \| shares	0
Granted (in shares) \| shares	200,000
Vested (in shares) \| shares	(29,063)
Forfeited (in shares) \| shares	0
Unvested the end of the period (in shares) \| shares	170,937
Weighted-Average Grant Date Fair Value
Unvested at the beginning of the period (in dollars per share) \| $ / shares	$ 0
Granted (in dollars per share) \| $ / shares	2.28
Vested (in dollars per share) \| $ / shares	2.29
Forfeited (in dollars per share) \| $ / shares	0
Unvested restricted common stock at the end of the period (in dollars per share) \| $ / shares	$ 2.28

Share-based Compensation Plans - Schedule of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Number of Options
Granted (in shares)	0	0
Outstanding at end of the year (in shares)	7,500
Weighted Average Exercise Price
Outstanding at end of the year (in dollars per share)	$ 40.2
Stock Options
Number of Options
Outstanding at beginning of the year (in shares)	365,216
Granted (in shares)	4,000	84,765
Exercised (in shares)	0
Cancelled or forfeited (in shares)	(77,848)
Outstanding at end of the year (in shares)	291,368	365,216
Exercisable (in shares)	246,819
Weighted Average Remaining Contractual Term (years)
Weighted Average Remaining Contractual Term, Outstanding (in years)	4 years 7 months 6 days	5 years 9 months 18 days
Weighted Average Remaining Contractual Term, Exercisable (in years)	4 years 1 month 6 days
Aggregate Intrinsic Value, Outstanding	$ 0	$ 20
Aggregate Intrinsic Value, Exercisable	$ 0
Weighted Average Exercise Price
Outstanding at beginning of the year (in dollars per share)	$ 184.45
Granted (in dollars per share)	3.82
Exercised (in dollars per share)	0
Cancelled or forfeited (in dollars per share)	157.79
Outstanding at end of the year (in dollars per share)	189.09	$ 184.45
Exercisable (in dollars per share)	$ 214.28

Leases

12 Months Ended

Dec. 31, 2023

Leases [Abstract]

Leases

9. Leases

In May 2021 the Company signed a 12-month membership agreement to lease space with WeWork at 501 Boylston Street, Boston, Massachusetts, commencing on August 1, 2021. The agreement was extended for six months on August 1, 2022. The 12-month agreement and 6-month extension are accounted for as short-term leases. The lease agreement was terminated during the year ended December 31, 2023. The Company recorded $0.1 million and $0.1 million, respectively, in lease expense associated with the membership agreement during the years ended December 31, 2023, and 2022.

On September 15, 2020, the Company entered into a Sublease Termination Agreement (the "Sublease Termination Agreement") to terminate its sublease of 15,700 rentable square feet, of its leased premises under the Head Lease. Under the terms of the Sublease Termination Agreement, the subtenant was relieved of its obligation to

provide future cash rental payments to the Company. The agreements requiring the former subtenant to provide licensed rooms and services to the Company free of charge through the original sublease term survived the sublease termination. The Company gained access to the licensed rooms and services beginning in the third quarter of 2021. The letter of credit security deposit related to the sublease was released.

The Company determined that the Sublease Termination Agreement constituted a non-monetary exchange under ASC 845 Nonmonetary Transactions (“ASC 845”) where, in return for the free rooms and the services, the Company agreed to terminate its rights and obligations under the sublease agreement. In accordance with ASC 845, the Company determined that the accounting for the transaction should be based on the fair value of assets or services involved. During the year ended December 31, 2020, the Company estimated the fair value of the rooms and services to be approximately $1.5 million and $2.9 million, respectively.

The Company determined that the licensed rooms represent a lease under ASC Topic 842 Leases. The Company obtained control of the rooms in the third quarter of 2021 and the prepaid rooms balance of approximately $1.4 million was reclassified from other assets to a ROU asset. The related lease expense is recognized on a straight-line basis over the lease term of 8.88 years. The Company recorded $0.2 million and $0.4 million of lease expense during the years ended December 31, 2023 and 2022, respectively. The Company determined that the licensed services represent a non-lease component, which is recognized separately from the lease component for this asset class. The expense related to the licensed services is recognized on a straight-line basis over the period the services are received. The Company recorded $0.1 million and $0.2 million for the years ended December 31, 2023 and 2022, respectively. Both the lease expense and services expense are recognized as a component of research and development costs in the consolidated statements of operations and comprehensive loss.

After the closing of the Asset Purchase Agreement, the Company had no plans in the foreseeable future to use the licensed rooms and the Company is restricted from subleasing the rooms. In August 2023, the ROU asset and other assets were fully impaired, and the Company recognized a $3.3 million impairment loss during the year ended December 31, 2023.

Discontinued Operations - Schedule of significant non-cash item for the discontinued operations that are included in the accompanying consolidated statements of cash flows (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Share-based compensation expense	$ 505	$ 1,161

Grant Revenue

12 Months Ended

Dec. 31, 2023

Disaggregation of Revenue [Line Items]

Grant Revenue

16. Grant Revenue

In August 2021, the Company was approved to receive funding from the PTC Grant for the Phase 2 study of CNS sGC stimulation in AD with vascular features. The granting period is July 1, 2021, to December 31, 2022, and the Company received an award of $2.0 million. The Company determined that this transaction is non-reciprocal as there is not considered to be a commensurate value exchanged with the Alzheimer's Association as the funding provider. Where commensurate value is not exchanged for goods and services provided, a recipient assesses whether the grant is conditional or unconditional. The Company considered all conditions and barriers associated with this grant and determined the grant is conditional and revenue will be recognized upon achieving certain milestones and incurring internal costs specifically covered by this grant. Under ASC 958-605, revenues will be recognized as the Company incurs expenses related to the PTC Grant.

The Company incurred approximately $0.1 million and approximately $0.6 million of allowable expenses and recognized a corresponding amount of grant revenue for the years ended December 31, 2023 and 2022.

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References + Details

- Definition

The entire disclosure of revenue from contract with customer to transfer good or service and to transfer nonfinancial asset. Includes, but is not limited to, disaggregation of revenue, credit loss recognized from contract with customer, judgment and change in judgment related to contract with customer, and asset recognized from cost incurred to obtain or fulfill contract with customer. Excludes insurance and lease contracts.

+ References

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+ Details

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2023

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

2. Summary of Significant Accounting Policies

Segment Information

Operating segments are components of an enterprise for which separate financial information is available and is evaluated regularly by the Company's President who is the chief operating decision maker in deciding how to allocate resources and in assessing performance. The Company currently operates in one reportable business segment - human therapeutics.

Discontinued Operations

In accordance with ASC 205-20 “Presentation of Financial Statements: Discontinued Operations”, a disposal of a component of an entity or a group of components of an entity is required to be reported as discontinued operations if the disposal represents a strategic shift that has (or will have) a major effect on an entity’s operations and financial results. In the period in which the component meets held-for-sale or discontinued operations criteria the major current assets, non-current assets, current liabilities, and non-current liabilities shall be reported as components of total assets and liabilities separate from those balances of the continuing operations and disclosed in the notes to financial statements. At the same time, the results of all discontinued operations, less applicable income taxes, shall be reported as components of net loss separate from the net income (loss) of continuing operations.

The Transferred Assets met the definition of a discontinued operation. Accordingly, the Company has classified the results of the Transferred Assets as discontinued operations in its consolidated statements of operations for all periods presented. All assets and liabilities associated with the Transferred Assets were classified as assets and liabilities of discontinued operations in the Note 4, "Discontinued Operations". All amounts included in the notes to the consolidated financial statements relate to continuing operations unless otherwise noted. For additional information, see Note 4, “Discontinued Operations”.

Variable Interest Entities

The Company reviews each legal entity in which it has a financial interest to determine whether or not the entity is a variable interest entity, or VIE. If the entity is a VIE, the Company assesses whether or not it is the primary beneficiary of that VIE based on a number of factors, including (i) which party has the power to direct the activities that most significantly affect the VIE’s economic performance, (ii) the parties’ contractual rights and responsibilities pursuant to any contractual agreements and (iii) which party has the obligation to absorb losses or the right to receive benefits from the VIE. If the Company determines that it is the primary beneficiary of a VIE, it consolidates the financial statements of the VIE into its consolidated financial statements at the time that determination is made. On a quarterly basis, the Company evaluates whether it continues to be the primary beneficiary of any consolidated VIEs. If the Company determines that it is no longer the primary beneficiary of a consolidated VIE, or no longer has a variable interest in the VIE, the Company deconsolidates the VIE in the period that the determination is made.

Investment

The Company accounts for investments in equity securities without a readily determinable fair value at cost, minus impairment. If the Company identifies observable price changes in orderly transactions for an identical or a similar investment of the same issuer, the Company will measure the equity security at fair value as of the date that the observable transaction occurred in accordance with ASC Topic 321, Investments-Equity Securities.

Use of Estimates

The preparation of consolidated financial statements in accordance with U.S. generally accepted accounting principles ("GAAP") requires the Company’s management to make estimates and judgments that may affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements, and the amounts of expenses during the reported periods. On an ongoing basis, the Company’s management evaluates its estimates, judgments and methodologies. Significant estimates and

assumptions in the consolidated financial statements include those related to revenue, fair value determination of other investment, impairment of long-lived assets, valuation procedures for right-of-use ("ROU") assets and operating lease liabilities, income taxes, including the valuation allowance for deferred tax assets, research and development expenses, contingencies, share-based compensation and going concern. The Company bases its estimates on historical experience and on various other assumptions that are believed to be reasonable, the results of which form the basis for making judgments about the carrying values of assets and liabilities. Actual results may differ materially from these estimates under different assumptions or conditions. Changes in estimates are reflected in reported results in the period in which they become known.

Cash and Cash Equivalents

The Company considers all highly liquid investment instruments with a remaining maturity when purchased of three months or less to be cash equivalents. Investments qualifying as cash equivalents may consist of money market funds and overnight repurchase agreements. The carrying amount of cash equivalents approximates fair value.

Property and Equipment

Property and equipment are recorded at cost, and are depreciated when placed into service using the straight-line method based on their estimated useful lives as follows:


Asset Description		Estimated Useful Life (In Years)
Computer equipment		3
Software		3

Software costs incurred during the preliminary project stage are expensed as incurred, while costs incurred during the application development stage are capitalized and amortized over the estimated useful life of the software. The Company also capitalizes costs related to specific upgrades and enhancements when it is probable the expenditures will result in additional functionality. Maintenance and training costs related to software obtained for internal use are expensed as incurred.

Costs for capital assets not yet placed into service have been capitalized as construction in progress and are depreciated in accordance with the above guidelines once placed into service. Maintenance and repair costs are expensed as incurred.

Property and equipment that is no longer required for the business is considered disposed of when it ceases to be used. Disposals are either sold or retired and the net book value is removed from the consolidated balance sheet and a corresponding gain or loss on the sale or disposal is recognized as a component of operating expenses in the consolidated statements of operations and comprehensive loss.

Fair Value of Investment Instruments

Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. Financial assets and liabilities carried at fair value are to be classified and disclosed in one of the following three levels of the fair value hierarchy, of which the first two are considered observable and the last is considered unobservable:

•

Level 1 — Quoted prices in active markets for identical assets or liabilities.

•

Level 2 — Observable inputs (other than Level 1 quoted prices), such as quoted prices in active markets for similar assets or liabilities, quoted prices in markets that are not active for identical or similar assets or liabilities, or other inputs that are observable or can be corroborated by observable market data.

•

Level 3 — Unobservable inputs that are supported by little or no market activity and that are significant to determining the fair value of the assets or liabilities, including pricing models, discounted cash flow methodologies and similar techniques.

Foreign Currency Translation Adjustment

The functional currency of the Company’s foreign subsidiary is its local currency, the Swiss franc. The assets and liabilities of the Company’s foreign subsidiary are translated into U.S. dollars at exchange rates in effect at the balance sheet date. Income and expense items are translated at the average exchange rates prevailing during the period. The cumulative translation effect for the Company’s foreign subsidiary is included as a foreign currency translation adjustment in the consolidated statements of stockholders’ equity and as a component of comprehensive loss in the consolidated statements of operations and comprehensive loss.

The Company’s intercompany accounts are typically denominated in the functional currency of the foreign subsidiary. Gains and losses resulting from the re-measurement of intercompany balances are recorded in the consolidated statements of operations.

Accounts Receivable

The Company makes judgments as to its ability to collect outstanding receivables and provides an allowance for receivables when collection becomes doubtful. Provisions are made based upon a specific review of all significant outstanding invoices. The Company’s receivables primarily relate to amounts earned under a development agreement with Ironwood, licensing agreement, and supply agreement. The Company believes that credit risks associated with these agreements are not significant. To date, the Company has not had significant write-offs of bad debt and the Company did not have an allowance for doubtful accounts as of December 31, 2023 or 2022.

Impairment of Long-Lived Assets

The Company regularly reviews the carrying amount of its long-lived assets to determine whether indicators of impairment may exist, which warrant adjustments to carrying values or estimated useful lives. If indications of impairment exist, projected future undiscounted cash flows associated with the asset are compared to the carrying amount to determine whether the asset’s value is recoverable. If the carrying value of the asset exceeds such projected undiscounted cash flows, the asset will be written down to its estimated fair value. There were no significant impairments of long-lived assets for the years ended December 31, 2023 or 2022, except for the impairment loss of ROU assets recognized during the year ended December 31, 2023.

Leases

Effective January 1, 2019, the Company adopted Accounting Standards Codification (“ASC”) Topic 842, Leases (“ASC 842”) using the optional transition method. The adoption of ASC 842 represents a change in accounting principle that aims to increase transparency and comparability among organizations by requiring the recognition of right-of-use assets and lease liabilities on the balance sheet for both operating and finance leases. In addition, the standard requires enhanced disclosures that meet the objective of enabling financial statement users to assess the amount, timing, and uncertainty of cash flows arising from leases. The reported results for the years ended December 31, 2023 and 2022 reflect the application of ASC 842 guidance.

The recognition of right-of-use assets and lease liabilities related to the Company’s operating leases under ASC 842 has had a material impact on the Company’s consolidated financial statements.

As part of the ASC 842 adoption, the Company has used certain practical expedients outlined in the guidance. These practical expedients include:

•

Account policy election to use the short-term lease exception by asset class;

•

Election of the practical expedient package during transition, which includes:

•

An entity need not reassess whether any expired or existing contracts are or contain leases.

•

An entity need not reassess the classification for any expired or existing leases. As a result, all leases that were classified as operating leases in accordance with ASC 840 are classified as operating leases under ASC 842, and all leases that were classified as capital leases in accordance with ASC 840 are classified as finance leases under ASC 842.

•

An entity need not reassess initial direct costs for any existing leases.

The Company had a property lease for its headquarters location at 301 Binney Street, Cambridge, MA (the “Head Lease”). The Company determined if the arrangement was a lease at the inception of the contract. The asset component of the Company’s operating leases was recorded as operating lease right-of-use assets, and the liability component was recorded as current portion of operating lease liabilities and operating lease liabilities, net of current portion, in the Company’s consolidated balance sheets.

ROU assets and operating lease liabilities are recognized based on the present value of lease payments over the lease term at the commencement date. The Company uses an incremental borrowing rate based on the information available at commencement date in determining the present value of lease payments if an implicit rate of return is not provided with the lease contract. Operating lease right-of-use assets are adjusted for incentives received.

Lease cost was recognized on a straight-line basis over the lease term, and included amounts related to short-term leases. Variable lease costs that do not depend on an index or rate were recognized as incurred.

ROU assets and operating lease liabilities were remeasured upon certain modifications to leases using the present value of remaining lease payments and estimated incremental borrowing rate upon lease modification. The difference between the remeasured ROU assets and the operating lease liabilities were recognized as a gain or loss in operating expenses. The Company reviewed any changes to its lease agreements for potential modifications and/or indicators of impairment of the respective ROU asset. During the year ended December 31, 2023, the Company recorded $3.3 million for impairment of ROU asset. See Note 9, “Leases,” for additional information.

Revenue

Upon executing a revenue generating arrangement, the Company assesses whether it is probable the Company will collect consideration in exchange for the good or service it transfers to the customer. To determine revenue recognition for arrangements that the Company determines are within the scope of ASC Topic 606, Revenue from Contracts with Customers (“ASC 606”), it performs the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the Company satisfies the performance obligations. The Company must develop assumptions that require significant judgment to determine the stand-alone selling price for each performance obligation identified in the contract. The assumptions that are used to determine the stand-alone selling price may include forecasted revenues, development timelines, reimbursement rates for personnel costs, discount rates and probabilities of technical and regulatory success. The Company derives revenue from (1) license agreement and (2) supply agreement which are fully described in Note 15, License Agreement.

The Company generates revenue from research and development grants under contracts with third parties that do not create customer-vendor relationships. The Company’s research and development grants are non-exchange transactions and are not within the scope of ASC Topic 606, Revenue from Contracts with Customers (“ASC 606”). Contribution revenue earned from activities performed pursuant to research and development grants is reported as grant revenue in the Company’s consolidated statements of operations. Revenue from these grants is recognized as the Company incurs qualifying expenses as stipulated by the terms of the respective grant. Cash received from grants in advance of incurring qualifying expenses is recorded as deferred revenue. The Company records revenue and a corresponding receivable when qualifying costs are incurred before receiving payment from the grants.

Research and Development Costs

The Company expenses research and development costs to operations as incurred. The Company defers and capitalizes nonrefundable advance payments made by the Company for research and development activities until the related goods are received or the related services are performed. The Company estimates the period over which such services will be performed and the level of effort to be expended in each period. If actual timing of performance or the level of effort varies from the estimate, the Company will adjust the amounts recorded accordingly. The Company has not experienced any material differences between accrued or prepaid costs and actual costs since inception.

Research and development expenses are comprised of costs incurred in performing research and development activities, which may include salary, benefits and other employee-related expenses; share-based compensation expense; laboratory supplies and other direct expenses; facilities expenses; overhead expenses; third-party contractual costs relating to nonclinical studies and clinical trial activities and related contract manufacturing expenses, development of manufacturing processes and regulatory registration of third-party manufacturing facilities; and other outside expenses.

General and Administrative Expenses

The Company expenses general and administrative costs to operations as incurred. General and administrative expense consists of compensation, share-based compensation, benefits and other employee-related expenses for personnel in the Company’s administrative, finance, legal, information technology, business development and human resource functions. Other costs include the legal costs of pursuing patent protection of the Company’s intellectual property, general and administrative related facility costs, insurance costs and professional fees for accounting and legal services.

Income taxes

The Company is primarily subject to U.S. Federal and Massachusetts state income taxes. For federal and state income taxes, deferred tax assets and liabilities are recognized based upon temporary differences between the financial statement and the tax basis of assets and liabilities. Deferred income taxes are based upon prescribed rates and enacted laws applicable to periods in which differences are expected to reverse. A valuation allowance is recorded when it is more likely than not that some portion or all of the deferred tax assets will not be realized. Accordingly, the Company provides a valuation allowance, if necessary, to reduce deferred tax assets to amounts that are realizable.

The tax positions taken or expected to be taken in the course of preparing the Company tax returns are required to be evaluated to determine whether the tax positions are “more-likely-than-not” of being sustained by the applicable tax authority. Tax positions not deemed to meet a more-likely-than-not threshold would be recorded as a tax expense in the current year. The determination as to whether the tax benefit will more likely than not be realized is based upon the technical merits of the tax position as well as consideration of the available facts and circumstances. It does not consider the likelihood of whether or not the IRS will review the position. Cyclerion evaluates uncertain tax positions on a quarterly basis and adjusts the level of the liability to reflect any subsequent changes in the relevant facts surrounding the uncertain positions. Any changes to these estimates, based on the actual results obtained and/or a change in assumptions, could affect Cyclerion's income tax provision in future periods. There were no uncertain tax positions that require accrual or disclosure in the consolidated financial statements as of December 31, 2023, and 2022. The Company’s policy is to recognize interest and penalties related to income tax, if any, in income tax expense. As of December 31, 2023 and 2022, the Company has no accruals for interest or penalties related to income tax matters.

Patent Costs

Patent fees and patent related costs in connection with filing and prosecuting patent applications are expensed as incurred and are classified as general and administrative expenses in the accompanying consolidated financial statements. The Company incurred and recorded as operating expense legal and other fees related to

patents of approximately $1.1 million and $1.7 million for the years ended December 31, 2023 and 2022, respectively.

Interest and Other Income, Net

For the year ended December 31, 2023 and 2022, interest and other income, net consisted of a $0.4 million and $0.3 million of interest income related to interest generated from the Company's cash and cash equivalents balances, respectively.

Subsequent Events

The Company considers events or transactions that have occurred after the balance sheet date of December 31, 2023, but prior to the filing of the financial statements with the Securities and Exchange Commission, to provide additional evidence relative to certain estimates or to identify matters that require additional recognition or disclosure. Subsequent events have been evaluated through the filing of the financial statements accompanying this Annual Report on Form 10-K. See Note 17, Subsequent Events.

Recently Issued Accounting Pronouncements

From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (“FASB”) or other standard setting bodies that are adopted by the Company as of the specified effective date. Except as discussed elsewhere in the notes to the consolidated financial statements, the Company did not adopt any new accounting pronouncements during the years ended December 31, 2023 and 2022, that had a material effect on its consolidated financial statements.

Recently Adopted Accounting Pronouncements

In June 2016 the FASB issued ASU 2016-13, Financial Instruments-Credit Losses. This standard requires entities to measure all expected credit losses for financial assets held at the reporting date based on historical experience, current conditions, and reasonable and supportable forecasts. As a smaller reporting company, ASU 2016-13 became effective for the Company for fiscal years beginning after December 15, 2022. The Company adopted ASU 2016-13 in the first quarter of 2023, and the adoption of this standard did not have any impact on the Company's financial position or results of operations.

No other accounting standards known by the Company to be applicable to it that have been issued by the FASB or other standard-setting bodies and that do not require adoption until a future date are expected to have a material impact on the Company’s consolidated financial statements upon adoption.

Share-based Compensation Plans (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($) TradingDay $ / shares shares	Dec. 31, 2022 USD ($) $ / shares shares
Share-based Compensation Plans
Share-based compensation \| $	$ 1,067	$ 6,252
Number of shares vested	0	2,500
outstanding stock options	7,500
Weighted average exercise price \| $ / shares	$ 40.2
Expected period to recognize the expense	4 months 6 days
Total intrinsic value \| $	$ 0	$ 0
Granted (in shares)	0	0
Research and development
Share-based Compensation Plans
Share-based compensation \| $	$ 421	$ 2,915
General and administrative
Share-based Compensation Plans
Share-based compensation \| $	$ 646	$ 3,337
Restricted Stock Units
Share-based Compensation Plans
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage	25.00%
Granted (in shares)	0
Vested (in shares)	37,675
Restricted Stock Awards
Share-based Compensation Plans
Granted (in shares)	200,000
Vested (in shares)	29,063
Vested upon grant	28,750
Restricted Stock Awards \| Director
Share-based Compensation Plans
Expected period to recognize the expense	3 years 6 months 10 days
Unrecognized share-based compensation expense \| $	$ 400
Restricted Stock Awards \| RSAs vest over 42-month period
Share-based Compensation Plans
Vested (in shares)	113,750
Restricted Stock Awards \| RSAs vest over 6-month period
Share-based Compensation Plans
Vested (in shares)	2,500
Restricted Stock Awards \| RSAs vest over 48-month period
Share-based Compensation Plans
Vested (in shares)	55,000
Performance stock options
Share-based Compensation Plans
Threshold consecutive trading days, used as a base for measurement of vesting of stock awards \| TradingDay	30
Performance stock options \| Minimum
Share-based Compensation Plans
Expected option term (in years)	4 years
Performance stock options \| Maximum
Share-based Compensation Plans
Expected option term (in years)	4 years 7 months 6 days
Stock Options
Share-based Compensation Plans
outstanding stock options	291,368	365,216
Weighted average exercise price \| $ / shares	$ 189.09	$ 184.45
Share based compensation expense \| $	$ 0	$ 0
Expected period to recognize the expense	3 years 5 months 15 days
Weighted average grant date fair value per option share \| $ / shares	$ 2.95	$ 18.2
Unrecognized share-based compensation expense \| $	$ 300
Granted (in shares)	4,000	84,765

Nature of Business (Details) $ / shares in Units, $ in Thousands			12 Months Ended		16 Months Ended	24 Months Ended
	Jul. 28, 2023 USD ($)	Sep. 03, 2020 USD ($)	Dec. 31, 2023 USD ($) $ / shares shares	Dec. 31, 2022 USD ($) $ / shares	Dec. 31, 2021 USD ($)	Dec. 31, 2023 USD ($) $ / shares	Mar. 31, 2023 USD ($) $ / shares shares	Nov. 15, 2019 Employee	May 03, 2019 Employee
Nature of Business
Cash consideration transferrred	$ 8,000
Operating expenses	$ 2,400		$ 12,951	$ 18,837
Equity investment in cash							$ 5,000
Preferred stock, par value (in dollars per share) \| $ / shares			$ 0	$ 0		$ 0
Cash commission of gross proceeds of sales of common stock, percentage		3.00%
Proceeds from stock purchase agreement			$ 5,000	$ 0
Common stock issued or sold under the ATM Offering					$ 3,353,059	$ 0
Net loss			(5,263)	(44,078)
Accumulated deficit			(264,417)	$ (259,154)		$ (264,417)
Issuance of common stock			$ 1,953
Series A Convertible Preferred Stock
Nature of Business
Preferred stock, shares issued \| shares							351,037
Preferred stock, par value (in dollars per share) \| $ / shares							$ 8.68
Common Stock
Nature of Business
Common stock shares issued \| shares							225,000
Issuance of common stock equity private placement and ATM (in shares) \| shares			225,000
ATM Offering \| Jefferies LLC
Nature of Business
Proceeds from stock purchase agreement					$ 12,500
ATM Offering \| Maximum \| Jefferies LLC
Nature of Business
Issuance of common stock		$ 50,000
Cyclerion GmbH
Nature of Business
Number of employees \| Employee									0
Cyclerion Securities Corporation
Nature of Business
Commercialization milestone payments			$ 585,000
Number of employees \| Employee								0
Tisento Therapeutics Holdings Inc
Nature of Business
Outstanding equity securities	10.00%

Fair Value of Financial Instruments

12 Months Ended

Dec. 31, 2023

Fair Value Disclosures [Abstract]

Fair Value of Financial Instruments

3. Fair Value of Financial Instruments

The Company’s cash equivalents are generally classified within Level 1 of the fair value hierarchy. The following tables present information about the Company’s financial assets measured at fair value on a recurring basis and indicate the level of the fair value hierarchy used to determine such fair values as of December 31, 2023 and December 31, 2022 (in thousands):


	Fair Value Measurements as of December 31, 2023:
	Level 1		Level 2		Level 3		Total
Cash equivalents:
Money market funds	$	7,244	$	—	$	—	$	7,244
Cash equivalents	$	7,244	$	—	$	—	$	7,244


	Fair Value Measurements as of December 31, 2022:
	Level 1		Level 2		Level 3		Total
Cash equivalents:
Money market funds	$	12,357	$	—	$	—	$	12,357
Cash equivalents	$	12,357	$	—	$	—	$	12,357

During the year ended December 31, 2023 and 2022, there were no transfers between levels. The fair value of the Company's cash equivalents, consisting of money market funds, is based on quoted market prices in active markets with no valuation adjustment.

The Company believes the carrying amounts of its prepaid expenses and other current assets, accounts payable, and accrued expenses approximate their fair value due to the short-term nature of these amounts.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Other Investment

12 Months Ended

Dec. 31, 2023

Investments, All Other Investments [Abstract]

Other Investment

5. Other Investment

On July 28, 2023, the Company closed the transactions contemplated by the Asset Purchase Agreement receiving proceeds of $8.0 million as cash consideration, approximately $2.4 million as reimbursement for certain operating expenses related to zagociguat and CY3018 programs for the period between signing and closing of the transaction, and 10% of all of Tisento Parent's outstanding equity securities which fair value was determined to be $5.3 million at the time of closing. The Company’s investment in Tisento Parent does not provide it with significant influence over Tisento Parent.

The Company has determined that the Company’s investment in Tisento Parent is an equity security, whereby such investment does not give the Company a controlling financial interest or significant influence over the investee. Further, the Company assessed the accounting for its investment in Tisento Parent in accordance with ASC 810-10, Consolidation—Overall. After determining that no scope exception applies under the guidance of ASC 810-10-15-12 and ASC 810-10-15-17, the Company concluded that it has a variable interest in Tisento Parent through its investment in Tisento Parent common stock. Tisento Parent does not have sufficient equity to finance its activities without additional subordinated financial support as Tisento Parent is a startup entity in its early

stages of raising funds and will require significant capital to advance its programs to commercial stage. Therefore, the Company concluded that its investment in Tisento Parent is a variable interest entity (“VIE”) in accordance with ASC 810-10-15-14(a) and is subject to potential consolidation under the VIE model. However, all activities that most significantly impact Tisento Parent and its subsidiary’s economic performance are directed by the Tisento Parent board and the board approves decisions by a simple majority. Based on the board composition, the Company determined that no one party has control over the Tisento Parent board and power is not shared because the activities that most significantly affect Tisento Parent and its subsidiary’s economic performance do not require the consent of all of the parties. Rather, all decisions are made by a simple majority vote of the Tisento Parent board. Therefore, because the Company controls no director of Tisento Parent, the Company cannot unilaterally direct any of the activities that most significantly impact Tisento Parent and its subsidiary’s economic performance. Accordingly, the Company does not hold a controlling financial interest in Tisento Parent. Because both criteria (a) and (b) above have to be met for the application of the guidance in ASC 810-10-25-44B and criteria (a) has not been met, The Company concluded that it should not consolidate Tisento under the VIE model.

Accordingly, the Company has accounted for the investment as a financial instrument without a readily determinable fair value. Such investment is recorded using the measurement alternative for investments without readily determinable fair values, whereby the investment is measured at cost less any impairment recorded or adjustments for observable price changes. An impairment loss is recognized in the consolidated statements of operations and comprehensive loss equal to the amount by which the carrying value exceeds the fair value of the investment. As of December 31, 2023, no impairment loss was recognized. The Company considers the cost of the investment to be the maximum exposure to loss as a result of its involvement with the non-affiliated entity.

The initial fair value of the investment in Tisento Parent was determined by reference to the risk-adjusted net assets value using the discounted cash flow method. The estimated net assets value of Tisento Parent includes the cash generated/used from the operations and the proceeds from equity financing. Valuations were derived by reference to observable valuation measures for comparable companies or transactions, including weighted average cost of capital (21% to 23%), terminal decline rate (25% to 75%) and the discount rate referenced by a two-year treasury rate of 4.01%.

Fair Value of Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2023

Fair Value Disclosures [Abstract]

Schedule of financial assets measured at fair value on a recurring basis and indicating the level of the fair value hierarchy


	Fair Value Measurements as of December 31, 2023:
	Level 1		Level 2		Level 3		Total
Cash equivalents:
Money market funds	$	7,244	$	—	$	—	$	7,244
Cash equivalents	$	7,244	$	—	$	—	$	7,244


	Fair Value Measurements as of December 31, 2022:
	Level 1		Level 2		Level 3		Total
Cash equivalents:
Money market funds	$	12,357	$	—	$	—	$	12,357
Cash equivalents	$	12,357	$	—	$	—	$	12,357

Workforce Reduction (Tables)

12 Months Ended

Dec. 31, 2023

Restructuring and Related Activities [Abstract]

Schedule of accrued liabilities activity allocated to Cyclerion in connection with the reduction in workforce

The following table summarizes the accrued liabilities activity recorded in connection with the reduction in workforce for the year ended December 31, 2023 (in thousands):


	Amounts accrued at December 31, 2022			Charges			Amount paid		Adjustments		Amounts accrued at December 31, 2023
Workforce reductions	$	(809	)	$	(565	)	$	1,374	$	—	$	—
Total	$	(809	)	$	(565	)	$	1,374	$	—	$	—

Discontinued Operations - Schedule of discontinued operations carrying amounts of major classes of assets and liabilities (Details) - Discontinued Operations $ in Thousands	Dec. 31, 2022 USD ($)
Assets of discontinued operations, Current
Prepaid expenses	$ 3
Other current assets	20
Total current assets of discontinued operations	23
Total assets of discontinued operations	23
Current liabilities of discontinued operations
Accounts payable	2,389
Accrued research and development costs	2,233
Accrued expenses and other current liabilities	155
Total current liabilities of discontinued operations	4,777
Total liabilities of discontinued operations	4,777
Net liabilities of discontinued operations	$ (4,754)

Loss per share

12 Months Ended

Dec. 31, 2023

Earnings Per Share [Abstract]

Loss per share

11. Loss per share

Basic and diluted net loss per common share is computed by dividing net loss by the weighted average number of common shares outstanding during the period as follows:


	Year Ended December 31,
	2023			2022
Numerator:
Net loss from continuing operations (in thousands)	$	(12,593	)	$	(18,246	)
Net gain (loss) from discontinued operations (in thousands)		7,330			(25,832	)
Total net loss (in thousands)		(5,263	)		(44,078	)

Denominator:
Weighted average shares used in calculating net gain (loss) per share — basic and diluted (in thousands) (*)		2,338			2,173

Net gain (loss) per share — basic and diluted
Net loss per share from continuing operations	$	(5.39	)	$	(8.40	)
Net gain (loss) per share from discontinued operations		3.14			(11.89	)
Total loss per share	$	(2.25	)	$	(20.28	)

*Adjusted retroactively for reverse stock split - see Note 1

We exclude shares of common stock related to Preferred Stock, stock options, RSUs and RSAs from the calculation of diluted net loss per share since the inclusion of such shares would be anti-dilutive. The following table sets forth potential shares that were considered anti-dilutive for the years ended December 31, 2023 and 2022:


	Year Ended December 31,
	2023		2022
Preferred Stock		351,037		—
Stock Options		298,868		380,595
RSUs		—		40,779
RSAs		170,937		—
		820,842		421,374

Discontinued Operations - Schedule of discontinued operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on disposal of discontinued operations	$ 15,752
Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenues	50	$ 1,328
Research and development	4,439	25,514
General and administrative	4,033	1,646
Total cost and expenses	8,472	27,160
Loss from operations	(8,422)	(25,832)
Gain on disposal of discontinued operations	15,752	0
Net gain (loss) from discontinued operations	7,330	(25,832)
Grants \| Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenues	$ 50	$ 1,328

Loss per share - Schedule Of Earnings Per Share Diluted By Common Class (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Dilutive securities, effect on basic earnings per share, options and restrictive stock units	$ 820,842	$ 421,374
Stock Options
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Dilutive securities, effect on basic earnings per share, options and restrictive stock units	298,868	380,595
Restricted Stock Units
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Dilutive securities, effect on basic earnings per share, options and restrictive stock units	0	40,779
Restricted Stock Awards
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Dilutive securities, effect on basic earnings per share, options and restrictive stock units	$ 170,937	$ 0
Preferred Stock
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Anti-dilutive securities excluded from the calculation of diluted loss per share	351,037	0

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 7,571	$ 13,382
Accounts receivable	0	96
Prepaid expenses	442	805
Other current assets	11	537
Total current assets	8,024	14,820
Operating lease right-of-use asset	0	1,218
Other investment	5,350	0
Other assets	0	2,041
Total assets	13,374	18,079
Current liabilities:
Accounts payable	1,198	2,970
Accrued research and development costs	90	2,275
Accrued expenses and other current liabilities	798	2,382
Total current liabilities	2,086	7,627
Commitments and contingencies (Note 8)	0	0
Stockholders' equity
Preferred shares, no par value, 500,000 shares authorized and 351,037 series A convertible preferred stock issued and outstanding at December 31, 2023	0	0
Common stock, no par value, 20,000,000 shares authorized at December 31,2023 and 2022;2,645,096 and 2,175,936 shares issued at December 31,2023 and 2022, respectively; 2,474,159 and 2,175,936 shares outstanding at December 31,2023, and 2022, respectively	0	0
Paid-in capital	275,717	269,626
Accumulated deficit	(264,417)	(259,154)
Accumulated other comprehensive loss	(12)	(20)
Total stockholders' equity	11,288	10,452
Total liabilities and stockholders' equity	$ 13,374	$ 18,079

Income Taxes

12 Months Ended

Dec. 31, 2023

Income Tax Disclosure [Abstract]

Income Taxes

12. Income Taxes

There was no provision for income taxes for the years ended December 31, 2023, and 2022, due to the Company’s operating losses and a full valuation allowance on deferred tax assets. Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes.

A reconciliation of income taxes computed using the U.S. federal statutory rate to that reflected in operations follows (in thousands):


	Year Ended December 31,
	2023			2022
U.S.	$	(5,181	)	$	(44,063	)
International		(82	)		(15	)
Loss before benefit from income taxes	$	(5,263	)	$	(44,078	)
Income tax benefit using U.S. federal statutory rate	$	(1,105	)	$	(9,256	)
State income taxes, net of federal benefit		(5	)		(2,693	)
Non-deductible share-based compensation		(9	)		266
Share-based compensation - shortfalls/(windfalls)		1,196			833
Permanent differences		1			14
Tax credits		(500	)		(1,652	)
Other		17			3
Change in valuation allowance		405			12,485
	$	—		$	—

The effective income tax rate is based upon the income for the year, the composition of the income in different countries, and adjustments, if any, for the potential tax consequences, benefits or resolutions of audits or other tax contingencies. Our income tax rate in foreign jurisdictions is lower than our income tax rate in the United States.

Deferred tax assets (liabilities) consist of the following as of December 31, 2023 and 2022 (in thousands):


	Year Ended December 31,
	2023			2022
Deferred tax assets:
Net operating loss carryforwards	$	48,535		$	47,079
Tax credit carryforwards		10,388			9,848
Share-based compensation		7,071			8,354
Property and equipment		—			1
Capitalized research and development		16,440			17,399
Accruals and reserves		2			340
Total deferred tax assets	$	82,436		$	83,021

Deferred tax liabilities:
Operating lease - right of use asset	$	—		$	(333	)
Prepaid sublease termination		—			(658	)
Total deferred tax liabilities		—			(991	)
Net deferred tax assets		82,436			82,030

Valuation allowance		(82,436	)		(82,030	)
Net deferred tax assets	$	—		$	—

Management has evaluated the positive and negative evidence bearing upon the possible realization of its deferred tax assets. Management has considered the Company's history of operating losses, in addition to the expected timing of the reversal of existing temporary differences and concluded, in accordance with the applicable accounting standards, that it is more likely than not that the Company will not realize the benefit of its deferred tax assets. Accordingly, the net deferred tax assets have been fully reserved at December 31, 2023 and December 31, 2022. Management reevaluates the positive and negative evidence on a quarterly basis.

The valuation allowance increased by approximately $0.4 million during the year ended December 31, 2023 primarily due to increases in capitalized research and development expenses, net operating losses, tax credit carryforwards and deferred tax assets related to share-based compensation.

The Company did not generate net operating loss carryforwards or tax credit carryforwards available for its use until its inception and operation as a standalone legal entity. At December 31, 2023 and 2022, Cyclerion has federal net operating loss carryforwards of approximately $177 million and $172 million, respectively, to offset future federal taxable income that will be carried forward indefinitely until utilized. As of December 31, 2023, and 2022, Cyclerion had state net operating loss carryforwards of approximately $178 million and $173 million, respectively, to offset future state taxable income, which will begin to expire in 2040 and will continue to expire through 2042. Cyclerion also had tax credit carryforwards of approximately $10.8 million and $10.2 million as of December 31, 2023 and 2022, respectively, to offset future federal and state income taxes. Federal credits begin to expire in 2040 and will continue to expire through 2041. State credits begin to expire in 2022 and continue through 2034.

The Company’s ability to use its operating loss carryforwards and tax credits to offset future taxable income could be subject to restrictions under Section 382 of the U.S. Internal Revenue Code of 1986, as amended (the “Internal Revenue Code”). These potential restrictions may limit the future use of the operating loss carryforwards and tax credits if certain ownership changes described in the Internal Revenue Code occur. Changes in stock ownership may occur that would create these limitations on the Company’s use of the operating loss carryforwards and tax credits. In such a situation, the Company may be required to pay income taxes, even though significant operating loss carryforwards and tax credits exist.

The Company has not as yet conducted a study of its research and development credit carry forwards. This study may result in an adjustment to the Company’s research and development credit carryforwards; however, until a study is completed and any adjustment is known, no amounts are being presented as an uncertain tax position. A full valuation allowance has been provided against the Company’s research and development credits, and if an adjustment is required, this adjustment would be offset by an adjustment to the valuation allowance. Thus, there would be no impact to the consolidated balance sheets or statements of operations if an adjustment were required.

Upon audit, taxing authorities may challenge all or part of an uncertain income tax position. While Cyclerion has no history of tax audits since its inception on a standalone basis, it may be subject to tax audits by federal and state taxing authorities in the future. Accordingly, Cyclerion regularly assesses the outcome of potential examinations in each of the taxing jurisdictions when determining the adequacy of the amount of unrecognized tax benefit recorded. Cyclerion had no unrecognized tax benefits as of December 31, 2023 and 2022. Cyclerion will recognize interest and penalties, if any, related to uncertain tax positions in income tax expense. As of December 31, 2023 and 2022, no interest or penalties have been accrued. There are no current federal or state income tax audits in progress.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480990/946-20-50-13

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
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-Name Accounting Standards Codification
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-Paragraph 1
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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-Paragraph 2
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-URI https://asc.fasb.org//1943274/2147479360/740-10-S99-2

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482603/740-30-50-2

+ Details

License Agreement - Additional Information (Details) - USD ($) $ in Thousands		12 Months Ended
	Jun. 03, 2021	Dec. 31, 2023	Dec. 31, 2022
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenues		$ 0	$ 297
Akebia Research License Agreement [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Up Front Payment Received	$ 3,000
Additional milestone cash payment	$ 585,000
Akbeia Supply Agreement [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenues		$ 300	$ 300

- Definition

Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(g)(1)(ii))
-Publisher FASB
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 323
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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Reference 6: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
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Reference 11: http://www.xbrl.org/2003/role/disclosureRef
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Reference 12: http://www.xbrl.org/2003/role/disclosureRef
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Reference 13: http://www.xbrl.org/2003/role/disclosureRef
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Reference 18: http://www.xbrl.org/2003/role/disclosureRef
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Reference 22: http://www.xbrl.org/2003/role/disclosureRef
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Reference 23: http://www.xbrl.org/2003/role/disclosureRef
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-Subparagraph (SX 210.9-05(b)(2))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479557/942-235-S99-1

+ Details

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2023

Accounting Policies [Abstract]

Schedule of Estimated Useful Lives of Property and Equipment

Property and equipment are recorded at cost, and are depreciated when placed into service using the straight-line method based on their estimated useful lives as follows:


Asset Description		Estimated Useful Life (In Years)
Computer equipment		3
Software		3

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (5,263)	$ (44,078)
Adjustments to reconcile net loss to net cash used in operating activities:
Gain on disposal of discontinued operations	(15,752)	0
Depreciation and amortization	0	65
Impairment Loss	3,304	0
Share-based compensation expense	1,067	6,252
Changes in operating assets and liabilities:
Accounts receivable	96	4
Prepaid expenses	363	123
Other current assets	160	(69)
Operating lease assets	108	184
Other assets	213	366
Accounts payable	(1,772)	1,142
Accrued research and development costs	(2,185)	(4,078)
Accrued expenses and other current liabilities	(1,584)	(522)
Net cash used in operating activities	(21,245)	(40,611)
CASH FLOWS FROM INVESTING ACTIVITIES:
Net proceeds from disposal of discontinued operations	10,402	0
Net cash provided by investing activities	10,402	0
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from stock purchase agreement	5,000	0
Proceeds from exercises of stock options and ESPP	24	29
Net cash provided by financing activities	5,024	29
Effect of exchange rate changes on cash and cash equivalents	8	3
Net decrease in cash and cash equivalents	(5,811)	(40,579)
Cash and cash equivalents, beginning of period	13,382	53,961
Cash and cash equivalents, end of period	7,571	13,382
Supplemental Cash Flow Information [Abstract]
Non-cash gain on disposal of discontinued operations	$ 5,350	$ 0

Grant Revenue (Additional Information) (Details) - USD ($) $ in Millions	12 Months Ended		18 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2022
Revenue Recognition and Deferred Revenue [Abstract]
PTC Grant Award			$ 2.0
Allowable Expenses on Grant Revenue	$ 0.1	$ 0.6

Consolidated Statements of Operations and Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Revenues [Abstract]
Revenue from development agreement	$ 0	$ 297
Total revenues	0	297
Cost and expenses:
Research and development	1,515	5,979
General and administrative	8,132	12,858
Impairment Loss	3,304	0
Total cost and expenses	12,951	18,837
Loss from operations	(12,951)	(18,540)
Interest and other income, net	358	294
Net loss from continuing operations	(12,593)	(18,246)
Discontinued operations:
Gain (loss) from discontinued operations	7,330	(25,832)
Net loss	$ (5,263)	$ (44,078)
*Net income (loss) per share - basic and diluted ()**
Net loss per share from continuing operations, basic	$ (5.39)	$ (8.4)
Income Loss from Discontinued Operations Basic	3.14	(11.89)
Basic net gain (loss) per share	(2.25)	(20.28)
Net loss per share from continuing operations, diluted	(5.39)	(8.4)
Income Loss from Discontinued Operations Diluted	3.14	(11.89)
Diluted net gain (loss) per share	$ (2.25)	$ (20.28)
Weighted average shares used in calculating:
Weighted Average Number of Shares Outstanding, Basic	2,338	2,173
Weighted Average Number of Shares Outstanding, Diluted	2,338	2,173
Other comprehensive loss:
Net loss	$ (5,263)	$ (44,078)
Other comprehensive loss:
Foreign currency translation adjustment gain	8	3
Comprehensive loss	$ (5,255)	$ (44,075)

Summary of Significant Accounting Policies - Segments and Cash (Details)	12 Months Ended
	Dec. 31, 2023 Segment
Segment Information
Number of reportable business segment	1

License Agreement

12 Months Ended

Dec. 31, 2023

License Agreement [Abstract]

License Agreement

15. License Agreement

Akebia License Agreement

On June 3, 2021, the Company and Akebia entered into a License Agreement (the “Akebia License Agreement”) relating to the exclusive worldwide license by the Company to Akebia of our rights to the development, manufacture, medical affairs and commercialization of pharmaceutical products containing the pharmaceutical compound known as praliciguat and other related products and forms thereof enumerated in the License Agreement (collectively, the “Products”). Pursuant to the Akebia License Agreement, Akebia will be responsible for all future research, development, regulatory, and commercialization activities for the Products.

Akebia paid a $3.0 million up-front payment to the Company upon signing of the License Agreement and the Company is eligible to receive additional milestone cash payments of up to $585 million in total potential future development, regulatory, and commercialization milestone payments for praliciguat. In addition to these cash milestone payments, Akebia will pay the Company tiered royalty payments on net sales in certain major markets at percentages ranging from the mid-single digits to the high-teens, subject to certain reductions and offsets.

Pursuant to the Akebia License Agreement, the Company determined the Akebia License Agreement represents a service arrangement under the scope of ASC 606. Given the reversion of the rights under the Akebia License Agreement represents a penalty in substance for a termination by Akebia, the contract term would be the stated term of the License Agreement.

The Company determined that the grant of license to our patents and trademarks, know how transfer, the assignment of regulatory submissions and trademarks and additional knowledge transfer assistance obligations represent a single promise and performance obligation to be transferred to Akebia over time due to the nature of the promises in the contract. The provision of development materials on hand was identified as a separate performance obligation. However, it is immaterial in the context of the contract as the development materials are low value and do not have an alternative use to the Company.

The consideration related to sales-based milestone payments, including royalties, will be recognized when the related sales occur as these amounts have been determined to relate predominantly to the license. The Company will re-evaluate the probability of achievement of the milestones and any related constraints each reporting period.

Akebia Supply Agreement

On August 3, 2021, the Company and Akebia entered into a Supply Agreement (the “Supply Agreement”) relating to the manufacturing by the Company of the Initial Supply of the Drug Product and placebo ("Initial Supply") for Akebia's use pursuant to the Akebia License Agreement. Akebia will pay the Company for the manufacturing costs at mutually agreed upon rates.

The Company determined the Supply Agreement has stand-alone value under the scope of ASC 606 and should not be combined with the Akebia License Agreement. Given that the Supply Agreement can be terminated at any time without cause with 30 days’ notice, the Company deemed the Supply Agreement to be a month-to-month contract. The manufacturing of the Initial Supply by the Company represents a single performance obligation and consideration related to the manufacturing costs will be recognized over time as costs are incurred. The Company recorded a de minimis amount and approximately $0.3 million, respectively, for the years ended December 31, 2023 and 2022, as revenue from the Supply Agreement.

Discontinued Operations

12 Months Ended

Dec. 31, 2023

Discontinued Operations and Disposal Groups [Abstract]

Discontinued Operations

4. Discontinued Operations

On May 11, 2023, the Company entered into the Purchase Agreement with Tisento for Tisento’s acquisition of substantially all of the assets comprising the Company’s zagociguat and CY3018 programs, in exchange for consideration at closing of $8.0 million, the reimbursement of employee expenses or R&D expenses of $2.4 million that Tisento reimbursed the Company for upon closing, and 10% of the issued and outstanding shares of Tisento Parent (Note 5). Upon closing of the transaction, the Company transferred certain fully depreciated software included within property and equipment to Tisento.

The carrying value of the disposal group was lower than its fair value, less costs to sell, and accordingly, a gain on disposal was recorded during the year ended December 31, 2023. The operations of the Transferred Assets are presented as discontinued for all periods presented. The transaction closed on July 28, 2023.

The following table presents the results of the discontinued operations for the year ended December 31, 2023 and 2022 (in thousands):


	Year Ended December 31,
	2023			2022
Revenues:
Revenue from grants	$	50		$	1,328
Total revenues		50			1,328
Cost and expenses:
Research and development		4,439			25,514
General and administrative		4,033			1,646
Total cost and expenses		8,472			27,160
Loss from operations		(8,422	)		(25,832	)
Gain on disposal of discontinued operations		15,752			—
Net gain (loss) from discontinued operations	$	7,330		$	(25,832	)

The following table summarizes the carrying amounts of major classes of assets and liabilities of discontinued operations as of December 31, 2022 (in thousands).


	December 31, 2022
Prepaid expenses	$	3
Other current assets		20
Total current assets of discontinued operations		23
Total assets of discontinued operations		23

Accounts payable		2,389
Accrued research and development costs		2,233
Accrued expenses and other current liabilities		155
Total current liabilities of discontinued operations		4,777
Total liabilities of discontinued operations		4,777
Net liabilities of discontinued operations	$	(4,754	)

The following table presents the significant non-cash item for the discontinued operations that are included in the accompanying consolidated statements of cash flows (in thousands):


	Year Ended December 31,
	2023		2022
Cash flows from operating activities:
Share-based compensation expense	$	505	$	1,161

The transaction consideration received from the sale of the Transferred Assets were as follows (in thousands):


	Amount
Closing payment	$	8,000
Expense reimbursement		2,402
Investment in Tisento Parent		5,350
Gross transaction consideration from the sale		15,752
Net assets sold		—
Gain on disposal of discontinued operations	$	15,752

During the year ended December 31, 2023, the Company incurred $1.3 million in closing costs associated with the sale of the Transferred Assets. The Company also incurred $0.9 million in transaction costs associated with the sale of the Transferred Assets during the year ended December 31, 2023, respectively. All of the closing and transaction costs were recognized as part of discontinued operations - general and administrative.

Defined Contribution Plan (Details) - USD ($)	12 Months Ended
Defined Contribution Plan (Details) - USD ($)	Dec. 31, 2023	Dec. 31, 2022
Defined Contribution Plan
401 (k) Savings Plan	us-gaap:QualifiedPlanMember
Matching contribution (as a percent of employee's contributions)	75.00%
Maximum amount of employer matching contribution	$ 6,000
Compensation expense related to the defined contribution 401(k) Savings Plan	$ 100,000	$ 200,000
Minimum
Defined Contribution Plan
Percent of compensation eligible employees may elect to contribute	1.00%
Maximum
Defined Contribution Plan
Percent of compensation eligible employees may elect to contribute	100.00%

Defined Contribution Plan

12 Months Ended

Dec. 31, 2023

Retirement Benefits [Abstract]

Defined Contribution Plan

13. Defined Contribution Plan

The Company has established a defined contribution 401(k) Savings Plan which allows eligible employees to contribute from 1% to 100% of their compensation, subject to certain IRS limits. The Company's contributions to the plan are at the sole discretion of the board of directors. Currently, the Company provides a matching contribution of 75% of the employee’s contributions, up to $6,000 annually.

Included in compensation expense is approximately $0.1 million and $0.2 million related to the defined contribution 401(k) Savings Plan for the years ended December 31, 2023 and 2022, respectively.

- Definition

The entire disclosure for retirement benefits.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 70
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480794/715-70-50-1

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 17
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480482/715-20-55-17

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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-Paragraph 1
-Subparagraph (d)(iv)(03)
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-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2023

Accounting Policies [Abstract]

Basis of Presentation

The consolidated financial statements and the related disclosures have been prepared in accordance with U.S. generally accepted accounting principles. In the opinion of management, the consolidated financial statements reflect all normal recurring adjustments considered necessary for a fair presentation of the Company’s financial position and the results of its operations for the fiscal years presented.

The consolidated financial statements include the financial statements of the Company and its wholly owned subsidiaries, Cyclerion GmbH, and Cyclerion Securities Corporation. All significant intercompany accounts and transactions have been eliminated in the preparation of the accompanying consolidated financial statements.

Segment Information

Discontinued Operations

Variable Interest Entities

Investment

Use of Estimates

Cash and Cash Equivalents

Property and Equipment

Property and equipment are recorded at cost, and are depreciated when placed into service using the straight-line method based on their estimated useful lives as follows:


Asset Description		Estimated Useful Life (In Years)
Computer equipment		3
Software		3

Fair Value of Investment Instruments

•

Level 1 — Quoted prices in active markets for identical assets or liabilities.

•

Foreign Currency Translation Adjustment

Accounts Receivable

Impairment of Long-Lived Assets

Leases

The recognition of right-of-use assets and lease liabilities related to the Company’s operating leases under ASC 842 has had a material impact on the Company’s consolidated financial statements.

As part of the ASC 842 adoption, the Company has used certain practical expedients outlined in the guidance. These practical expedients include:

•

Account policy election to use the short-term lease exception by asset class;

•

Election of the practical expedient package during transition, which includes:

•

An entity need not reassess whether any expired or existing contracts are or contain leases.

•

An entity need not reassess initial direct costs for any existing leases.

Revenue

Research and Development Costs

General and Administrative Expenses

Income taxes

Patent Costs

patents of approximately $1.1 million and $1.7 million for the years ended December 31, 2023 and 2022, respectively.

Interest and Other Income, Net

Subsequent Events

Recently Issued/Adopted Accounting Pronouncements

Recently Issued Accounting Pronouncements

Recently Adopted Accounting Pronouncements

Other Investment - Additional Information (Details) - USD ($) $ in Thousands		12 Months Ended
	Jul. 28, 2023	Dec. 31, 2023	Dec. 31, 2022
Investment Holdings, Other than Securities [Line Items]
Cash consideration transferrred	$ 8,000
Operating expenses	$ 2,400	$ 12,951	$ 18,837
Impairment loss on other investments		$ 0
Tisento Therapeutics Holdings Inc
Investment Holdings, Other than Securities [Line Items]
Outstanding equity securities	10.00%
Fair value of outstanding equity securities	$ 5,300
Treasury rate
Investment Holdings, Other than Securities [Line Items]
Net assets percentage	4.01%
Minimum \| Weighted average investment
Investment Holdings, Other than Securities [Line Items]
Net assets percentage	21.00%
Minimum \| Terminal decline rate
Investment Holdings, Other than Securities [Line Items]
Net assets percentage	25.00%
Maximum \| Weighted average investment
Investment Holdings, Other than Securities [Line Items]
Net assets percentage	23.00%
Maximum \| Terminal decline rate
Investment Holdings, Other than Securities [Line Items]
Net assets percentage	75.00%

Income Taxes - Reconciliation of income taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
U.S.	$ (5,181)	$ (44,063)
International	(82)	(15)
Loss before benefit from income taxes	(5,263)	(44,078)
Income tax benefit using U.S. federal statutory rate	(1,105)	(9,256)
State income taxes, net of federal benefit	(5)	(2,693)
Non-deductible share-based compensation	(9)	266
Share-based compensation - shortfalls/(windfalls)	1,196	833
Permanent differences	1	14
Tax credits	(500)	(1,652)
Other	17	3
Change in valuation allowance	405	12,485
Income Tax Expense (Benefit), Total	$ 0	$ 0

Share-based Compensation Plans

12 Months Ended

Dec. 31, 2023

Share-Based Payment Arrangement [Abstract]

Share-based Compensation Plans

10. Share-based Compensation Plans

In 2019, Cyclerion adopted share-based compensation plans. Specifically, Cyclerion adopted the 2019 Employee Stock Purchase Plan (“2019 ESPP”) and the 2019 Equity Incentive Plan (“2019 Equity Plan”). Under the 2019 ESPP, eligible employees may use payroll deductions to purchase shares of stock in offerings under the plan, and thereby acquire an interest in the future of the Company. The 2019 Equity Plan provides for stock options, restricted stock awards ("RSAs") and restricted stock units (“RSUs”).

Cyclerion also mirrored two of Ironwood Pharmaceuticals, Inc. ("Ironwood") existing plans, the Amended and Restated 2005 Stock Incentive Plan (“2005 Equity Plan”) and the Amended and Restated 2010 Employee, Director and Consultant Equity Incentive Plan (“2010 Equity Plan"). These mirror plans were adopted to facilitate the exchange of Ironwood equity awards for Cyclerion equity awards upon the Separation as part of the equity conversion. As a result of the Separation and in accordance with the EMA, employees of both companies retained their existing Ironwood vested options and received a pro-rata share of Cyclerion options, regardless of which company employed them post-Separation. For employees that were ultimately employed by Cyclerion, unvested Ironwood options and RSUs were converted to unvested Cyclerion options and RSUs.

The following table provides share-based compensation reflected in the Company’s consolidated statements of operations and comprehensive loss for the years ended December 31, 2023 and 2022 (in thousands):


	Year Ended December 31,
	2023		2022
Research and development	$	421	$	2,915
General and administrative		646		3,337
	$	1,067	$	6,252

Stock Options

Stock options granted under the Company’s equity plans generally have a ten-year term and vest over a period of four years, provided the individual continues to serve at the Company through the vesting dates. Options granted under all equity plans are exercisable at a price per share not less than the fair market value of the underlying common stock on the date of grant. The estimated fair value of options, including the effect of estimated forfeitures, is recognized over the requisite service period, which is typically the vesting period of each option.

A summary of stock option activity for the year ended December 31, 2023 is as follows:


						Weighted
				Weighted		Average		Average
				Average		Remaining		Intrinsic
	Number			Exercise		Contractual		Value (in
	of Options			Price		Term (Years)		thousands)
Outstanding as of December 31, 2022		365,216		$	184.45		5.8		20
Granted		4,000			3.82
Exercised		—			0.00
Cancelled or forfeited		(77,848	)		157.79
Outstanding as of December 31, 2023		291,368		$	189.09		4.6	$	—
Exercisable at December 31, 2023		246,819		$	214.28		4.1	$	—

During the years ended December 31, 2023 and 2022, the Company granted stock options to purchase an aggregate of 4,000 shares and 84,765 shares, respectively, at weighted average grant fair values per option share of $2.95 and $18.20 respectively.

There were no options exercised during the year ended December 31, 2023 and 2022.

As of December 31, 2023, the unrecognized share-based compensation expense, net of estimated forfeitures, related to all unvested time-based stock options held by the Company’s employees is $0.3 million and the weighted average period over which that expense is expected to be recognized is 3.46 years.

The weighted-average Black-Scholes assumptions used in estimating the fair value of the stock options granted by Cyclerion during the years ended December 31, 2023 and 2022 were as follows:


	Year ended December 31,
	2023			2022
Weighted average risk-free interest rate		3.47	%		1.93	%
Expected dividend yield		—			—
Expected option term (in years)		6.0			6.0
Expected stock price volatility		93.19	%		98.90	%

For the years ended December 31, 2023 and 2022, expected volatility was estimated using an average of the historical volatility of the common stock of a group of similar companies that were publicly traded. The Company will continue to apply this process until a sufficient amount of historical information regarding the volatility of its own stock price becomes available.

The Company has granted certain employees performance-based options to purchase shares of common stock. These options are subject to performance-based milestone vesting. During the year ended December 31, 2023, there were no shares that vested as a result of performance milestone achievements and 2,500 shares vested during the year ended December 31, 2022. The Company recorded a de minimis and no share-based compensation expense related to these performance-based options for the years ended December 31, 2023, and 2022, respectively.

Market-based Stock Options

The Company also has granted to certain employees stock options containing market conditions that vest upon the achievement of specified price targets of the Company’s share price for a period through December 31,

2024. Vesting is measured based upon the average closing price of the Company’s share price for any thirty consecutive trading days, subject to certain service requirements. Stock compensation cost is expensed on a straight-line basis over the derived service period for each stock price target within the award, ranging from approximately 4.0 to 4.6 years. The Company accelerates expense when a stock price target is achieved prior to the derived service period. The Company does not reverse expense recognized if the share price target(s) are ultimately not achieved but expense is reversed when a stock award recipient has a break in service prior to the completion of the derived service period. As of December 31, 2023, there were 7,500 outstanding stock options containing market conditions with a weighted average exercise price of $40.20. As of December 31, 2023, there was a de minimis amount of unrecognized compensation costs related to stock options containing market conditions, which is expected to be recognized over a weighted-average period of 0.35 years.

A summary of stock awards containing market conditions activity for the year ended December 31, 2023 is as follows:


						Weighted
				Weighted		Average		Aggregate
				Average		Remaining		Intrinsic
	Number of			Exercise		Contractual		Value (in
	Options			Price		Term (years)		thousands)
Outstanding as of December 31, 2022		15,000		$	40.20	$	6.9	$	—
Granted		—			—		—		—
Exercised		—			—		—		—
Cancelled or forfeited		(7,500	)	$	40.20	$	5.9	$	—
Outstanding as of December 31, 2023		7,500		$	40.20		5.9	$	—
Exercisable at December 31, 2023		—		$	—		—	$	—

No stock options containing market conditions were granted during the years ended December 31, 2023 and 2022.

Restricted Stock Units

The RSUs generally vest 25% per year on the approximate anniversary of the date of grant until fully vested, provided the employee remains continuously employed with the Company through each vesting date. Shares of the Company’s common stock are delivered to the employee upon vesting, subject to payment of applicable withholding taxes. The fair value of all RSUs is based on the market value of the Company’s common stock on the date of grant. Compensation expense, including the effect of estimated forfeitures, is recognized over the applicable service period.

A summary of RSU activity for the years ended December 31, 2023 is as follows:


				Weighted Average
	Number			Grant Date
	of Shares			Fair Value
Unvested as of December 31, 2022		40,772		$	15.30
Granted		—			—
Vested		(37,675	)		15.11
Forfeited		(3,097	)		17.50
Unvested as of December 31, 2023		—		$	—

Restricted Stock Awards

The Company granted 200,000 RSAs during the year ended December 31, 2023. 28,750 RSAs vest upon grant. 113,750 RSAs vest ratably over a 42-month period, 2,500 RSAs vest over a 6-month period and 55,000 RSAs vest ratably over a 48-month period, provided the grantee remains continuously as a director or an employee of the Company through each vesting date. Shares of the Company’s common stock are delivered to the employee upon vesting, subject to payment of applicable withholding taxes. The fair value of all RSAs is based on the market value

of the Company’s common stock on the date of grant. Compensation expense, including the effect of estimated forfeitures, is recognized over the applicable service period.

A summary of RSA activity for the years ended December 31, 2023 is as follows:


				Weighted Average
	Number			Grant Date
	of Shares			Fair Value
Unvested as of December 31, 2022		—		$	—
Granted		200,000			2.28
Vested		(29,063	)		2.29
Forfeited		—			—
Unvested as of December 31, 2023		170,937		$	2.28

As of December 31, 2023, the unrecognized share-based compensation expense, net of estimated forfeitures, related to all unvested RSAs held by the Company’s directors is $0.4 million and the weighted average period over which that expense is expected to be recognized is 3.53 years.

Share-based Compensation Plans - Summary of RSU activity (Details)	12 Months Ended
	Dec. 31, 2023 $ / shares shares
Weighted-Average Grant Date Fair Value
Expected period to recognize the expense	4 months 6 days
Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage	25.00%
Number of Shares
Unvested at the beginning of the period (in shares) \| shares	40,772
Granted (in shares) \| shares	0
Vested (in shares) \| shares	(37,675)
Forfeited (in shares) \| shares	(3,097)
Unvested the end of the period (in shares) \| shares	0
Weighted-Average Grant Date Fair Value
Unvested at the beginning of the period (in dollars per share) \| $ / shares	$ 15.30
Granted (in dollars per share) \| $ / shares	0
Vested (in dollars per share) \| $ / shares	15.11
Forfeited (in dollars per share) \| $ / shares	17.5
Unvested restricted common stock at the end of the period (in dollars per share) \| $ / shares	$ 0

Summary of Significant Accounting Policies - Schedule of Estimated Useful Lives of Property and Equipment (Details)	Dec. 31, 2023
Computer equipment
Property and Equipment
Estimated Useful Life (In Years)	3 years
Software
Property and Equipment
Estimated Useful Life (In Years)	3 years

Share-based Compensation Plans - Schedule of Weighted Average Assumptions used in estimating the fair value of the stock options (Details)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Weighted average risk-free interest rate	3.47%	1.93%
Expected dividend yield	0.00%	0.00%
Expected option term (in years)	6 years	6 years
Expected stock price volatility	93.19%	98.90%

Subsequent Events

12 Months Ended

Dec. 31, 2023

Subsequent Events [Abstract]

Subsequent Events

17. Subsequent Events

The Company has evaluated all events and transactions that occurred after the balance sheet date through the date the consolidated financial statements were issued and determined that there were no such events requiring recognition or disclosure in the consolidated financial statements.

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2023	Dec. 31, 2022
Preferred stock, par value (in dollars per share)	$ 0	$ 0
Preferred stock,shares authorized	500,000
Common stock, par value (in dollars per share)	$ 0	$ 0
Common stock, shares issued	2,645,096	2,175,936
Common stock, shares authorized	20,000,000	20,000,000
Common stock, shares outstanding	2,474,159	2,175,936
SeriesA Convertible Preferred Stock [Member]
Preferred stock, shares issued	351,037
Preferred stock,shared outstanding	351,037

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
Document and Entity Information - USD ($) $ in Millions	Dec. 31, 2023	Mar. 03, 2024	Jun. 30, 2023
Cover [Abstract]
Entity Registrant Name	CYCLERION THERAPEUTICS, INC.
Document Type	10-K
Document Period End Date	Dec. 31, 2023
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Shell Company	false
Entity Public Float			$ 7.1
Entity Common Stock, Shares Outstanding		2,710,096
Entity Central Index Key	0001755237
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	FY
Amendment Flag	false
Document Annual Report	true
Document Transition Report	false
Entity Tax Identification Number	83-1895370
Entity File Number	001-38787
Entity Incorporation, State or Country Code	MA
Entity Address, Address Line One	245 First Street, 18th Floor
Entity Address, City or Town	Cambridge
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02142
City Area Code	857
Local Phone Number	327-8778
Title of 12(b) Security	Common Stock, no par value
Trading Symbol	CYCN
Security Exchange Name	NASDAQ
Documents Incorporated by Reference	Portions of the registrant’s definitive Proxy Statement, to be filed pursuant to Regulation 14A under the Securities Exchange Act of 1934, for its 2024 Annual Meeting of Stockholders are incorporated by reference in Part III of this Form 10-K.
ICFR Auditor Attestation Flag	false
Document Financial Statement Error Correction [Flag]	false
Auditor Firm ID	42
Auditor Name	Ernst & Young LLP
Auditor Location	Boston, Massachusetts

Summary of Significant Accounting Policies - Revenue, Patent Costs, and Interest and Other Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Interest and other income, net
Interest and other income, net
Interest income generated from cash and cash equivalents balances	$ 0.4	$ 0.3
Patents
Patent Costs
Legal and other fees	$ 1.1	$ 1.7

Accrued Expenses and Other Current Liabilities

12 Months Ended

Dec. 31, 2023

Accrued Liabilities and Other Liabilities [Abstract]

Accrued Expenses and Other Current Liabilities

7. Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities consisted of the following (in thousands):


	December 31,		December 31,
	2023		2022
Accrued incentive compensation	$	—	$	238
Salaries		11		246
Accrued vacation		—		186
Professional fees		685		835
Accrued severance and benefit costs		—		809
Other		102		68
Accrued expenses and other current liabilities	$	798	$	2,382

Share-based Compensation Plans - Schedule of Share-based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation	$ 1,067	$ 6,252
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation	421	2,915
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation	$ 646	$ 3,337

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 35
-Paragraph 1D
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480483/718-10-35-1D

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Property and Equipment (Tables)

12 Months Ended

Dec. 31, 2023

Property, Plant and Equipment [Abstract]

Schedule of property and equipment, net

Property and equipment, net consisted of the following (in thousands):


	December 31,			December 31,
	2023			2022
Software	$	126		$	2,174
Computer equipment		—			7
Property and equipment, gross		126			2,181
Less: accumulated depreciation and amortization		(126	)		(2,181	)
Property and equipment, net	$	—		$	—

Nature of Business

12 Months Ended

Dec. 31, 2023

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Nature of Business

1. Nature of Business

Nature of Operations

Cyclerion Therapeutics, Inc. (“Cyclerion”, the “Company” or “we”) became an independent public company on April 1, 2019 after Ironwood Pharmaceuticals, Inc., or Ironwood, completed a tax-free spin-off of its sGC business, which we refer to herein as the "Separation". Cyclerion has one employee as of December 31, 2023.

At inception, Cyclerion was a biopharmaceutical company focused on the treatment of serious diseases with novel soluble guanylate cyclase ("sGC") stimulators in both the CNS and the periphery. The nitric oxide ("NO") sGC cyclic guanosine monophosphate ("cGMP") signaling pathway is a fundamental mechanism that precisely controls key aspects of physiology throughout the body. The NO-sGC-cGMP pathway regulates diverse and critical biological functions in both the central nervous system ("CNS") and the periphery and has been successfully targeted with several drugs.

Praliciguat is an orally administered, once-daily systemic sGC stimulator. On June 3, 2021, Cyclerion entered into a license agreement (as defined below) with Akebia Therapeutics Inc. (“Akebia”) relating to the exclusive worldwide license to Akebia of our rights to the development, manufacture, medical affairs and commercialization of pharmaceutical products containing praliciguat and other related products and forms thereof enumerated in such agreement. Cyclerion is eligible to receive up to $585 million in total potential future development, regulatory, and commercialization milestone payments. Cyclerion is also eligible to receive tiered, sales-based royalties ranging from single-digit to high-teen percentages and subject to reduction upon expiration of patent rights or the launch of a generic product.

Olinciguat is a phase 2 an orally administered, once-daily, vascular sGC stimulator that Cyclerion intends to out-license to an entity with strong cardiovascular and/or cardiopulmonary capabilities.

Zagociguat is a clinical-stage CNS-penetrant sGC stimulator that has shown rapid improvement in cerebral blood flow, functional brain connectivity, brain response to visual stimulus, cognitive performance, and biomarkers associated mitochondrial function and inflammation in clinical studies. CY3018 is a CNS-targeted sGC stimulator that preferentially localizes to the brain and has a pharmacology profile that suggests its potential for the treatment of neuropsychiatric diseases and disorders. On July 28, 2023, the Company sold Zagociguat and CY3018 to Tisento Therapeutics, Inc. (“Tisento”), a newly formed private company focused on their development, in exchange for $8.0 million in cash consideration, $2.4 million as reimbursement for certain operating expenses related to zagociguat and CY3018 for the period between signing and closing of the transaction, and 10% of all of Tisento’s parent’s outstanding equity securities. See “Asset Purchase Agreement” and “Note 4” below.

Cyclerion is actively evaluating other activities aimed at enhancing shareholder value, which may potentially include collaborations, licenses, mergers, acquisitions and/or other targeted investments.

The Company has shifted its strategy to identify, non-sGC stimulator assets within the CNS therapeutic area to build a new portfolio. If the Company identifies suitable new assets, they will develop the new assets and retain contract research, development and manufacturing organizations for these specific purposes. Additionally, Cyclerion plans to raise funds for further research and development activities associated with any new assets. The Company’s goal is to find the best combination of capital, capabilities, and transactions that will enable the advancement of current and any future assets the Company may acquire for patients in a way that maximizes shareholder value.

Cyclerion GmbH, a wholly owned subsidiary, was incorporated in Zug, Switzerland on May 3, 2019. The functional currency is the Swiss franc. Subsequent to December 31, 2023, the liquidation process for Cyclerion GmbH has been concluded and the subsidiary is pending deregistration from the commercial registry. Cyclerion GmbH has no employees.

Cyclerion Securities Corporation, a wholly owned subsidiary, was incorporated in Massachusetts on November 15, 2019 and was granted securities corporation status in Massachusetts for the 2019 tax year. Cyclerion Securities Corporation has no employees.

Stock Purchase Agreement

In March 2023, the Company entered into a stock purchase agreement with the Company's former Chief Executive Officer (the “CEO”) pursuant to which he invested $5 million in cash for 225,000 shares of common stock and 351,037 shares of Series A Convertible Preferred Stock of the Company at a price of $8.68 per share (after giving effect to the 1-for-20 reverse stock split the Company implemented on May 15, 2023). Such Series A Convertible Preferred Stock is convertible into shares of our common stock on a one-to-one basis. The closing of the equity investment took place on May 19, 2023, and (to comply with Nasdaq listing requirements) our shareholders approved such convertibility on July 19, 2023.

Asset Purchase Agreement

On May 11, 2023, the Company entered into an Asset Purchase Agreement (the “Asset Purchase Agreement”) with an investor group that included the former CEO, JW Celtics Investment Corp and JW Cycle Inc. which subsequently changed their names to Tisento Therapeutics Holdings Inc. (“Tisento Parent”) and Tisento. Upon the closing on July 28, 2023, of the transactions contemplated by the Asset Purchase Agreement, the Company sold to Tisento specified assets relating to the Company’s zagociguat and CY3018 programs (the "Transferred Assets") and Tisento assumed certain liabilities relating thereto, including, but not limited to (i) liabilities, costs and expenses arising after the date of the Asset Purchase Agreement relating to the employment of certain Cyclerion employees and the conduct of certain preclinical and clinical trial activities prior to the closing of the transactions contemplated by the Asset Purchase Agreement, and (ii) liabilities relating to such assets to the extent relating to the period after the closing of the transaction. In consideration for such sale and assumption, at such closing the Company received proceeds of $8.0 million as cash consideration, $2.4 million as reimbursement for certain operating expenses related to such assets for the period between signing and closing of the Asset Purchase Agreement, and shares of common stock of Tisento Parent comprising 10% of the then issued and outstanding equity securities of Tisento Parent immediately following such closing, subject to certain protections against dilution.

Reverse Stock Split

On May 15, 2023, the Company filed Articles of Amendment to the Company's Restated Articles of Organization with the Secretary of Commonwealth of Massachusetts to effect a 1-for-20 reverse stock split of the Company's issued and outstanding shares of common stock. The reverse stock split was reflected on the Nasdaq Capital Market beginning with the opening of trading on May 16, 2023. All share amounts and per share amounts disclosed in this Annual Report on Form 10-K have been adjusted retroactively to reflect the reverse stock split for all periods presented.

At-the-Market Offering

On September 3, 2020, the Company entered into a Sales Agreement (the “Sales Agreement”) with Jefferies LLC (“Jefferies”) with respect to an at-the-market offering (the “ATM Offering”) under the Shelf. Under the ATM Offering, the Company could offer and sell, from time to time at its sole discretion, shares of its common stock, having an aggregate offering price of up to $50.0 million through Jefferies as its sales agent. The Company agreed to pay Jefferies cash commissions of 3.0 percent of the gross proceeds of sales of common stock which could be sold under the Sales Agreement. Prior to January 1, 2022, the Company sold 3,353,059 shares of its common stock for net proceeds of $12.5 million under the ATM Offering, since entering into the Sales Agreement. No shares of common stock have been issued or sold under the ATM Offering in 2022 or 2023. The Shelf expired in July 31, 2023. Due to the current market value of our publicly traded common stock held by non-affiliates, our ability to raise future funding though a shelf offering will be limited.

Basis of Presentation

Going Concern

At each reporting period, in accordance with Accounting Standards Codification ("ASC") 205-40, Going Concern, the Company evaluates whether there are conditions or events that raise substantial doubt about the Company’s ability to continue as a going concern within one year after the date that the financial statements are issued. The Company’s evaluation entails analyzing prospective operating budgets and forecasts for expectations of the Company’s cash needs and comparing those needs to the current cash and cash equivalent balances. The Company is required to make certain additional disclosures if it concludes substantial doubt exists and it is not alleviated by the Company’s plans or when its plans alleviate substantial doubt about the Company’s ability to continue as a going concern.

This evaluation initially does not take into consideration the potential mitigating effect of management’s plans that have not been fully implemented as of the date the financial statements are issued. When substantial doubt exists under this methodology, management evaluates whether the mitigating effect of its plans sufficiently alleviates substantial doubt about the Company’s ability to continue as a going concern. The mitigating effect of management’s plans, however, is only considered if both (1) it is probable that the plans will be effectively implemented within one year after the date that the financial statements are issued, and (2) it is probable that the plans, when implemented, will mitigate the relevant conditions or events that raise substantial doubt about the entity’s ability to continue as a going concern within one year after the date that these consolidated financial statements are issued. In performing its analysis, management excluded certain elements of its operating plan that cannot be considered probable. Under ASC 205-40, the future receipt of potential funding from future partnerships, equity or debt issuances, certain cost reduction measures and the potential milestones from the Akebia agreement cannot be considered probable at this time because these plans are not entirely within the Company’s control and/or have not been approved by the Board of Directors as of the date of these consolidated financial statements.

The Company expects that its cash, cash equivalents and marketable securities as of December 31, 2023, will be sufficient to fund operations through the first quarter of 2025, however the Company will need to obtain additional funding to sustain operations as it expects to continue to generate operating losses for the foreseeable future. The Company's expectation to generate negative operating cash flows in the future and the need for additional funding to support its planned operations, raise substantial doubt regarding the Company’s ability to continue as a going concern. Management's plans to alleviate the conditions that raise substantial doubt include reduced spending, and the pursuit of additional capital. Management has concluded the likelihood that its plan to successfully obtain sufficient funding, or adequately reduce expenditures, while reasonably possible, is less than probable. Accordingly, the Company has concluded that substantial doubt exists about the Company’s ability to continue as a going concern. The accompanying financial statements have been prepared on a going concern basis, which contemplates the realization of assets and satisfaction of liabilities in the ordinary course of business. The financial statements do not include any adjustments relating to the recoverability and classification of recorded asset amounts or the amounts and classification of liabilities that might result from the outcome of the uncertainties described above.

Property and Equipment

12 Months Ended

Dec. 31, 2023

Property, Plant and Equipment [Abstract]

Property and Equipment

. Property and Equipment

Property and equipment, net consisted of the following (in thousands):


	December 31,			December 31,
	2023			2022
Software	$	126		$	2,174
Computer equipment		—			7
Property and equipment, gross		126			2,181
Less: accumulated depreciation and amortization		(126	)		(2,181	)
Property and equipment, net	$	—		$	—

As of December 31, 2023, and 2022, the Company’s property and equipment was primarily located in Boston, Massachusetts.

During the year ended December 31, 2023, the Company did not record depreciation and amortization expenses. The Company recorded $0.1 million of depreciation and amortization expenses for the year ended December 31, 2022.

Discontinued Operations (Tables)

12 Months Ended

Dec. 31, 2023

Discontinued Operations and Disposal Groups [Abstract]

Schedule of discontinued operations

The following table presents the results of the discontinued operations for the year ended December 31, 2023 and 2022 (in thousands):


	Year Ended December 31,
	2023			2022
Revenues:
Revenue from grants	$	50		$	1,328
Total revenues		50			1,328
Cost and expenses:
Research and development		4,439			25,514
General and administrative		4,033			1,646
Total cost and expenses		8,472			27,160
Loss from operations		(8,422	)		(25,832	)
Gain on disposal of discontinued operations		15,752			—
Net gain (loss) from discontinued operations	$	7,330		$	(25,832	)

The following table summarizes the carrying amounts of major classes of assets and liabilities of discontinued operations as of December 31, 2022 (in thousands).


	December 31, 2022
Prepaid expenses	$	3
Other current assets		20
Total current assets of discontinued operations		23
Total assets of discontinued operations		23

Accounts payable		2,389
Accrued research and development costs		2,233
Accrued expenses and other current liabilities		155
Total current liabilities of discontinued operations		4,777
Total liabilities of discontinued operations		4,777
Net liabilities of discontinued operations	$	(4,754	)

The following table presents the significant non-cash item for the discontinued operations that are included in the accompanying consolidated statements of cash flows (in thousands):


	Year Ended December 31,
	2023		2022
Cash flows from operating activities:
Share-based compensation expense	$	505	$	1,161

Schedule of transaction consideration received from the sale of the Transferred Assets

The transaction consideration received from the sale of the Transferred Assets were as follows (in thousands):


	Amount
Closing payment	$	8,000
Expense reimbursement		2,402
Investment in Tisento Parent		5,350
Gross transaction consideration from the sale		15,752
Net assets sold		—
Gain on disposal of discontinued operations	$	15,752

- Definition

Tabular disclosure of information related to a disposal group. Includes, but is not limited to, a discontinued operation, disposal classified as held-for-sale or disposed of by means other than sale or disposal of an individually significant component.

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+ Details

Income Taxes - Deferred tax assets (liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Deferred tax assets:
Net operating loss carryforwards	$ 48,535	$ 47,079
Tax credit carryforwards	10,388	9,848
Share-based compensation	7,071	8,354
Property and equipment	0	1
Capitalized research and development	16,440	17,399
Accruals and reserves	2	340
Total deferred tax assets	82,436	83,021
Deferred tax liabilities:
Operating lease - right of use asset	0	(333)
Prepaid sublease termination	0	(658)
Total deferred tax liabilities	0	(991)
Net deferred tax assets	82,436	82,030
Valuation allowance	(82,436)	(82,030)
Net deferred tax assets	$ 0	$ 0

Property and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Property and Equipment
Property and equipment. gross	$ 126	$ 2,181
Less: accumulated depreciation and amortization	(126)	(2,181)
Property and equipment, net	0	0
Depreciation and amortization	0	65
Property and Equipment
Property and Equipment
Depreciation and amortization	0	100
Software
Property and Equipment
Property and equipment. gross	126	2,174
Computer and office equipment
Property and Equipment
Property and equipment. gross	$ 0	$ 7

Accrued Expenses and Other Current Liabilities (Tables)

12 Months Ended

Dec. 31, 2023

Accrued Liabilities and Other Liabilities [Abstract]

Schedule of accrued expenses and other current liabilities

Accrued expenses and other current liabilities consisted of the following (in thousands):


	December 31,		December 31,
	2023		2022
Accrued incentive compensation	$	—	$	238
Salaries		11		246
Accrued vacation		—		186
Professional fees		685		835
Accrued severance and benefit costs		—		809
Other		102		68
Accrued expenses and other current liabilities	$	798	$	2,382

Workforce Reduction

12 Months Ended

Dec. 31, 2023

Restructuring and Related Activities [Abstract]

Workforce Reduction

14. Workforce Reduction

Workforce Reductions

On October 6, 2022, the Company began a reduction of its current workforce by thirteen (13) full-time employees to align its resources with its current priorities of focusing on a mitochondrial disease-focused strategy. The workforce reduction was completed in the fourth quarter of 2022.

The Company recorded total costs related to the 2022 Workforce Reduction of approximately $1.3 million, including a de minimis amount of stock-based compensation from the modification of certain share-based equity awards.

The Company had further reductions of workforce in 2023 in connection with the sale of the Transferred Assets to Tisento and change to the Company’s strategy. The Company recorded total costs of approximately $0.6 million related to the reduction in workforce during 2023.

The following table summarizes the accrued liabilities activity recorded in connection with the reduction in workforce for the year ended December 31, 2023 (in thousands):


	Amounts accrued at December 31, 2022			Charges			Amount paid		Adjustments		Amounts accrued at December 31, 2023
Workforce reductions	$	(809	)	$	(565	)	$	1,374	$	—	$	—
Total	$	(809	)	$	(565	)	$	1,374	$	—	$	—

Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Accrued Liabilities and Other Liabilities [Abstract]
Accrued incentive compensation	$ 0	$ 238
Salaries	11	246
Accrued vacation	0	186
Professional fees	685	835
Accrued severance and benefit costs	0	809
Other	102	68
Accrued expenses and other current liabilities	$ 798	$ 2,382

Leases - Summary (Details) - USD ($) $ in Millions	12 Months Ended
Leases - Summary (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022	Aug. 01, 2022	May 31, 2021
Leases
Impairment of ROU asset	$ 3.3
Term of lease	8 years 10 months 17 days
Licensed Room
Leases
lease expense	$ 0.2	$ 0.4
License and Service
Leases
lease expense	0.1	0.2
WeWork
Leases
Term of lease			12 months	12 months
Renewal term			6 months
Total lease costs	$ 0.1	$ 0.1

Share-based Compensation Plans (Tables)

12 Months Ended

Dec. 31, 2023

Share-Based Payment Arrangement [Abstract]

Schedule of share-based compensation expense


	Year Ended December 31,
	2023		2022
Research and development	$	421	$	2,915
General and administrative		646		3,337
	$	1,067	$	6,252

Schedule of stock option activity

A summary of stock option activity for the year ended December 31, 2023 is as follows:


						Weighted
				Weighted		Average		Average
				Average		Remaining		Intrinsic
	Number			Exercise		Contractual		Value (in
	of Options			Price		Term (Years)		thousands)
Outstanding as of December 31, 2022		365,216		$	184.45		5.8		20
Granted		4,000			3.82
Exercised		—			0.00
Cancelled or forfeited		(77,848	)		157.79
Outstanding as of December 31, 2023		291,368		$	189.09		4.6	$	—
Exercisable at December 31, 2023		246,819		$	214.28		4.1	$	—

Schedule of weighted-average assumptions used in estimating the fair value of the stock options

The weighted-average Black-Scholes assumptions used in estimating the fair value of the stock options granted by Cyclerion during the years ended December 31, 2023 and 2022 were as follows:


	Year ended December 31,
	2023			2022
Weighted average risk-free interest rate		3.47	%		1.93	%
Expected dividend yield		—			—
Expected option term (in years)		6.0			6.0
Expected stock price volatility		93.19	%		98.90	%

Summary of stock awards containing market conditions activity

A summary of stock awards containing market conditions activity for the year ended December 31, 2023 is as follows:


						Weighted
				Weighted		Average		Aggregate
				Average		Remaining		Intrinsic
	Number of			Exercise		Contractual		Value (in
	Options			Price		Term (years)		thousands)
Outstanding as of December 31, 2022		15,000		$	40.20	$	6.9	$	—
Granted		—			—		—		—
Exercised		—			—		—		—
Cancelled or forfeited		(7,500	)	$	40.20	$	5.9	$	—
Outstanding as of December 31, 2023		7,500		$	40.20		5.9	$	—
Exercisable at December 31, 2023		—		$	—		—	$	—

Summary of RSU activity

A summary of RSU activity for the years ended December 31, 2023 is as follows:


				Weighted Average
	Number			Grant Date
	of Shares			Fair Value
Unvested as of December 31, 2022		40,772		$	15.30
Granted		—			—
Vested		(37,675	)		15.11
Forfeited		(3,097	)		17.50
Unvested as of December 31, 2023		—		$	—

Summary of RSA activity

A summary of RSA activity for the years ended December 31, 2023 is as follows:


				Weighted Average
	Number			Grant Date
	of Shares			Fair Value
Unvested as of December 31, 2022		—		$	—
Granted		200,000			2.28
Vested		(29,063	)		2.29
Forfeited		—			—
Unvested as of December 31, 2023		170,937		$	2.28

Discontinued Operations - Additional Information (Details) - USD ($) $ in Thousands			12 Months Ended
	Jul. 28, 2023	May 11, 2023	Dec. 31, 2023	Dec. 31, 2022
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration on acquisition transferred	$ 8,000
Research and development expense			$ 1,515	$ 5,979
Closing costs associated with sale of Transferred Assets			1,300
Transaction costs associated with sale of Transferred Assets			$ 900
Tisento Therapeutics Holdings Inc
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Equity securities, percentage	10.00%
Tisento Therapeutics Holdings Inc \| Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration on acquisition transferred		$ 8,000
Research and development expense		$ 2,400
Equity securities, percentage		10.00%

Loss per share (Tables)

12 Months Ended

Dec. 31, 2023

Earnings Per Share [Abstract]

Schedule of basic and diluted earnings per share

Basic and diluted net loss per common share is computed by dividing net loss by the weighted average number of common shares outstanding during the period as follows:


	Year Ended December 31,
	2023			2022
Numerator:
Net loss from continuing operations (in thousands)	$	(12,593	)	$	(18,246	)
Net gain (loss) from discontinued operations (in thousands)		7,330			(25,832	)
Total net loss (in thousands)		(5,263	)		(44,078	)

Denominator:
Weighted average shares used in calculating net gain (loss) per share — basic and diluted (in thousands) (*)		2,338			2,173

Net gain (loss) per share — basic and diluted
Net loss per share from continuing operations	$	(5.39	)	$	(8.40	)
Net gain (loss) per share from discontinued operations		3.14			(11.89	)
Total loss per share	$	(2.25	)	$	(20.28	)

*Adjusted retroactively for reverse stock split - see Note 1

Schedule of earnings per share diluted by common class

The following table sets forth potential shares that were considered anti-dilutive for the years ended December 31, 2023 and 2022:


	Year Ended December 31,
	2023		2022
Preferred Stock		351,037		—
Stock Options		298,868		380,595
RSUs		—		40,779
RSAs		170,937		—
		820,842		421,374

Commitments and Contingencies - Additional Information (Details) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($)
Commitments and Contingencies Disclosure [Abstract]
Payment to former chief financial officer	$ 0.1

Fair Value of Financial Instruments (Details) - Recurring - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Cash equivalents:
Total cash equivalents	$ 7,244	$ 12,357
Level 1
Cash equivalents:
Total cash equivalents	7,244	12,357
Money market funds
Cash equivalents:
Total cash equivalents	7,244	12,357
Money market funds \| Level 1
Cash equivalents:
Total cash equivalents	$ 7,244	$ 12,357

Workforce Reduction (Details) $ in Thousands		12 Months Ended
Workforce Reduction (Details) $ in Thousands	Oct. 06, 2022 USD ($) Employees	Dec. 31, 2023 USD ($)
Restructuring Cost And Reserve [Line Items]
Beginning of period		$ (809)
Charges		(565)
Amount paid		1,374
Adjustments		0
End of period		0
Workforce Reductions
Restructuring Cost And Reserve [Line Items]
Beginning of period		(809)
Charges		(565)
Amount paid		1,374
Adjustments		0
End of period		0
Current workforce reductions \| October 2022 Current Workforce Reduction
Restructuring Cost And Reserve [Line Items]
Reduction in workforce, number of employees \| Employees	13
Restructuring costs	$ 1,300
Current workforce reductions \| 2023 Further Workforce Deductions
Restructuring Cost And Reserve [Line Items]
Restructuring costs		$ 600