Cyclerion Therapeutics, Inc.

You should carefully review and consider the information regarding certain factors which could materially affect our business, financial condition or future results set forth under the heading “Risk Factors” in Part I, Item 1A of our Annual Report on Form 10-K for the fiscal year ended December 31, 2025. There have been no material changes in our risk factors since our Annual Report on Form 10-K for the year ended December 31, 2025, except as set forth below:

Risks Related to the Proposed Merger

Failure to complete, or delays in completing, the potential Merger could materially and adversely affect Cyclerion’s results of operations, business, financial results, and/or common stock price.

On April 1, 2026, Cyclerion and Korsana entered into the Merger Agreement, which agreement was subsequently amended on April 17, 2026, pursuant to which, among other matters, and subject to the satisfaction or waiver of the conditions set forth in the Merger Agreement, First Merger Sub will merge with and into Korsana, with Korsana continuing as a wholly owned subsidiary of Cyclerion and the surviving corporation of the First Merger and, immediately following the First Merger and as part of the same overall transaction as the First Merger, Korsana will merge with and into Second Merger Sub as part of the Second Merger, with Second Merger Sub continuing as a wholly owned subsidiary of Cyclerion and the surviving entity of the Second Merger. Consummation of the Merger is subject to certain closing conditions, a number of which are not within Cyclerion’s control. Any failure to satisfy these required conditions to closing may prevent, delay or otherwise materially adversely affect the completion of the transaction. Cyclerion cannot predict with certainty whether or when any of the required closing conditions will be satisfied or if another uncertainty may arise and cannot assure you that it will be able to successfully consummate the Merger as currently contemplated under the Merger Agreement or at all.

Cyclerion’s efforts to complete the Merger could cause substantial disruptions in, and create uncertainty surrounding, its business, which may materially adversely affect its results of operation and its business. Uncertainty as to whether the Merger will be completed in a timely manner or at all may affect Cyclerion’s ability to retain and motivate existing employees. Uncertainty as to whether the Merger will be completed in a timely manner or at all could adversely affect Cyclerion’s business and its relationship with collaborators, suppliers, vendors, regulators, and other business partners. The adverse effects of the pendency of the transaction could be exacerbated by any delays in completion of the transaction or termination of the Merger Agreement.

Even if the Merger is approved by the stockholders of Korsana and Cyclerion, specified conditions must be satisfied or, to the extent permitted by applicable law, waived to complete the Merger. Cyclerion cannot assure you that all of the conditions to the consummation of the Merger will be satisfied or waived. If the conditions are not satisfied or waived, the Merger may not occur or the closing may be delayed.

Cyclerion and Korsana may mutually agree to waive the condition to the Merger requiring approval for listing on Nasdaq, and if such condition is waived, the Combined Company’s stock may not be listed on Nasdaq following completion of the Merger.

Pursuant to the Merger Agreement, Cyclerion agreed, to the extent required by the rules and regulations of Nasdaq, to use its commercially reasonable efforts to cause the shares of Cyclerion Common Stock being issued in the Merger to be approved for listing on Nasdaq at or prior to the First Effective Time. Additionally, under the Merger Agreement, each of Cyclerion’s and Korsana’s obligation to complete the Merger is subject to the satisfaction or waiver by each of the parties of various conditions, including that the shares of Cyclerion Common

Stock to be issued in the Merger have been approved for listing (subject to official notice of issuance) on Nasdaq as of the closing of the Merger. In the event that the shares of Cyclerion Common Stock to be issued in the Merger are not approved for listing on Nasdaq, it is possible that Cyclerion and Korsana may mutually agree to waive the applicable condition and nonetheless proceed with completing the Merger. If such condition is waived, Cyclerion will not recirculate an updated proxy statement/prospectus, nor will it solicit a new vote of shareholders prior to proceeding with the Merger. If Cyclerion proceeds with the Merger in these circumstances, the Combined Company’s stock may not be listed on Nasdaq.

If the Combined Company’s stock is not listed on Nasdaq following completion of the Merger, trading of the shares could be conducted in the over-the-counter market or on an electronic bulletin board established for unlisted securities such as the Pink Sheets or the OTC Bulletin Board. In such event, it is likely that there would be significantly less liquidity in the trading of the common stock of the Combined Company; decreases in institutional and other investor demand for the shares, coverage by securities analysts, market making activity and information available concerning trading prices and volume; and fewer broker dealers willing to execute trades in the common stock of the Combined Company. Also, it may be difficult for the Combined Company to raise additional capital if the Combined Company’s common stock is not listed on a major exchange. The occurrence of any of these events could result in a further decline in the market price of the common stock of the Combined Company and could have a material adverse effect on the Combined Company.

The Exchange Ratio for the Merger will not change or otherwise be adjusted based on the market price of Cyclerion Common Stock.

Applying the Exchange Ratio, based on Cyclerion’s capitalization as of December 31, 2025 and Korsana’s capitalization as of March 31, 2026 and taking into account Cyclerion’s current cash position, each share of Korsana Common Stock is currently estimated to be entitled to receive approximately 1.1009 shares of Cyclerion Common Stock. Each share of Korsana Series Seed Preferred Stock will be converted into the right to receive a number of shares of Cyclerion Series B Preferred Stock, equal to the Exchange Ratio divided by 1,000. Applying the Exchange Ratio, the former Korsana securityholders immediately before the Merger are expected to own approximately 98.5% of the aggregate number of shares of the Combined Company’s capital stock following the Merger (on a fully-diluted basis), and Cyclerion shareholders immediately before the Merger are expected to own approximately 1.5% of the aggregate number of shares of the Combined Company capital stock following the Merger (on a fully-diluted basis), subject to certain assumptions, including, but not limited to, Cyclerion’s net cash as of closing being equal to $0. In the event Cyclerion’s Net Cash is less than or greater than $0, the Exchange Ratio will be adjusted such that the number of shares issued to Korsana’s pre-closing securityholders will be decreased or increased, as applicable, and Cyclerion shareholders will own a smaller or larger percentage, as applicable, of the Combined Company following the consummation of the Merger.

Any changes in the market price of Cyclerion’s stock before the completion of the First Merger will not affect the number of shares Korsana stockholders will be entitled to receive pursuant to the Merger Agreement. Therefore, if before the completion of the First Merger, the market price of Cyclerion Common Stock increases from the market price on the date of the Merger Agreement, then Korsana stockholders could receive merger consideration with substantially more value for their shares of Korsana capital stock than the parties had negotiated when they established the Exchange Ratio. Similarly, if before the completion of the First Merger, the market price of Cyclerion Common Stock declines from the market price on the date of the Merger Agreement, then Korsana stockholders could receive merger consideration with substantially lower value. The Merger Agreement does not include a price-based termination right.

The issuance of Cyclerion Common Stock, including the shares of Cyclerion Common Stock issuable upon conversion of Cyclerion Series B Preferred Stock, to Korsana stockholders pursuant to the Merger Agreement and the resulting change in control from the First Merger must be approved by Cyclerion shareholders, and the Merger Agreement and transactions contemplated thereby must be approved by the Korsana stockholders. Failure to obtain these approvals would prevent the closing of the Merger.

Before the Merger can be completed, Cyclerion shareholders must approve, among other things, the issuance of Cyclerion Common Stock, including shares of Cyclerion Common Stock issuable upon conversion of Cyclerion Series B Preferred Stock, to Korsana stockholders pursuant to the Merger Agreement and the resulting change in control from the First Merger, and Korsana stockholders must adopt the Merger Agreement and approve the Merger and the related transactions. Failure to obtain the required stockholder approvals may result in a material delay in, or the abandonment of, the Merger. Any delay in completing the Merger may materially adversely affect the timing and benefits that are expected to be achieved from the Merger.

In general, neither Cyclerion nor Korsana is obligated to complete the Merger if there is a material adverse effect affecting the other party between April 1, 2026, the date of the Merger Agreement, and the closing of the Merger. However, certain types of causes are excluded from the concept of a “material adverse effect.” Such exclusions include, but are not limited to, changes in general economic or political conditions, industry-wide changes, changes resulting from the announcement of the Merger, natural disasters, pandemics, other public health events or force majeure events and changes in U.S. generally accepted accounting principles. Therefore, if any of these events were to occur and adversely affect Cyclerion or Korsana, the other party would still be obliged to consummate the closing of the Merger notwithstanding such material adverse effect. If any such adverse effects occur and Cyclerion consummates the closing of the Merger, the stock price of the Combined Company may suffer. This in turn may reduce the value of the Merger to the shareholders of Cyclerion, Korsana or both.

If the Merger is not completed, Cyclerion’s stock price may decline significantly.

The market price of Cyclerion Common Stock is subject to significant fluctuations. Market prices for securities of pharmaceutical, biotechnology and other life science companies have historically been particularly volatile. In addition, the market price of Cyclerion Common Stock will likely be volatile based on whether shareholders and other investors believe that Cyclerion can complete the Merger or otherwise raise additional capital to support Cyclerion’s operations if the Merger is not consummated and another strategic transaction cannot be identified, negotiated and consummated in a timely manner, if at all. The volatility of the market price of Cyclerion Common Stock has been and may be exacerbated by low trading volume. Additional factors that may cause the market price of Cyclerion Common Stock to fluctuate include:

• announcements of the results of its future clinical trials, discussions with regulators, and regulatory approval decisions;

• the loss of key employees;

• future sales of Cyclerion Common Stock;

• general and industry-specific economic conditions that may affect Cyclerion’s research and development expenditures; and

• period-to-period fluctuations in financial results.

Moreover, the stock markets in general have experienced substantial volatility that has often been unrelated to the operating performance of individual companies. These broad market fluctuations may also adversely affect the trading price of Cyclerion Common Stock. In the past, following periods of volatility in the market price of a company’s securities, stockholders have often instituted class action securities litigation against such companies.

If Cyclerion completes the Merger, the Combined Company will need to raise additional capital and satisfy certain contractual obligations by issuing equity securities or additional debt or through licensing arrangements, which may cause significant dilution to the Combined Company’s shareholders or restrict the Combined Company’s operations.

In connection with the Merger, Korsana and Cyclerion entered into the Securities Purchase Agreement with certain investors, including existing investors of Korsana, pursuant to which the investors agreed to purchase, in the aggregate, approximately $380.0 million of Korsana Common Stock and Korsana Pre-Funded Warrants in the

Korsana Pre-Closing Financing immediately prior to the closing of the Merger. The closing of the Korsana Pre-Closing Financing is conditioned upon the satisfaction or waiver of the conditions to the closing of the Merger as well as certain other conditions. The Korsana Common Stock and Korsana Pre-Funded Warrants issued in the Korsana Pre-Closing Financing will result in dilution to all securityholders of the Combined Company (i.e., both Cyclerion’s pre-Merger securityholders and former Korsana securityholders).

In addition, as a result of Cyclerion’s assumption of the Paragon ADOA in connection with the Merger, the Combined Company will be subject to the obligation to grant to Parasa on December 31, 2026, warrants to purchase a number of shares equal to 1.00% of the outstanding shares of Cyclerion Common Stock as of the date of the grant on a fully-diluted basis, with an exercise price equal to the fair market value of the underlying shares on the grant date. Such warrants granted will result in further dilution to all securityholders of the Combined Company.

A significant portion of the Combined Company’s securities will be restricted from immediate resale. Holders should be aware that transfers of the Combined Company’s securities pursuant to Rule 144 may be limited as Rule 144 is not available, subject to certain exceptions, for the resale of securities initially issued by shell companies (other than business combination related shell companies) or issuers that have been at any time previously a shell company. Cyclerion’s expected disposal of Cyclerion’s historical assets and operations in connection with the Merger is expected to make Cyclerion a shell company. Cyclerion anticipates that following the consummation of the Merger, the Combined Company will no longer be a shell company. As a result, Cyclerion anticipates that holders will not be able to sell their restricted Combined Company securities pursuant to Rule 144 without registration until one year after Cyclerion files the Current Report on Form 8-K following the closing that includes the required Form 10 information that reflects that the Combined Company is no longer a shell company.

Cyclerion is expected to be deemed a shell company. As a result, if Cyclerion completes the Merger, the Combined Company will be subject to more stringent reporting requirements, offering limitations and resale restrictions.

Cyclerion’s or the Combined Company’s expected disposal of Cyclerion’s historical assets and operations prior to or following the Merger is expected to make Cyclerion a shell company. As such, the Combined Company would be subject to the requirements applicable to shell company business combinations. The requirements applicable to shell company business combinations are as follows:

• investors who (i) are affiliates of Korsana at the time the Merger is submitted for the vote or consent of Korsana stockholders, (ii) receive securities of the Combined Company in the Merger (i.e., Rule 145(c)

securities), and (iii) publicly offer or sell such securities, will be deemed to be engaged in a distribution of such securities, and therefore to be underwriters with respect to resales of those securities, and accordingly such securities may not be included in the Form S-1 resale registration statement anticipated to be filed after the closing of the Merger unless such securities are sold only in a fixed price offering in which such investors are named as underwriters in the prospectus; and

The foregoing SEC requirements would increase the Combined Company’s time and cost of raising capital, offering stock under equity plans, and complying with securities laws. Further, such requirements will add burdensome restrictions on the resale of Combined Company shares by affiliates of Korsana and any holders of “restricted” or “control” securities.

Some of Cyclerion’s and Korsana’s directors and executive officers have interests in the Merger that are different from yours and that may influence them to support or approve the Merger without regard to your interests.

Directors and executive officers of Cyclerion and Korsana have interests in the Merger that are different from, or in addition to, the interests of other Cyclerion shareholders generally. These interests with respect to Cyclerion’s directors and executive officers may include, among others, retention bonus payments, extension of exercisability periods of previously issued stock option grants, severance payments if employment is terminated in a qualifying termination in connection with the Merger and rights to continued indemnification, expense advancement and insurance coverage.

Further, certain current members of the Korsana Board will continue as directors of the Combined Company after the First Effective Time, and, following the closing of the Merger, will be eligible to be compensated as non-employee directors of the Combined Company pursuant to Cyclerion’s non-employee director compensation policy that is expected to remain in place following the First Effective Time.

The Cyclerion Board was aware of and considered those interests, among other matters, in reaching their decisions to approve and adopt the Merger Agreement, approve the Merger, and recommend the approval of the Merger Agreement to Cyclerion and Korsana stockholders. These interests, among other factors, may have influenced the directors and executive officers of each company to support or approve the Merger.

Cyclerion shareholders and Korsana stockholders may not realize a benefit from the Merger commensurate with the ownership dilution they will experience in connection with the Merger, including the conversion of Korsana Common Stock issued in the Korsana Pre-Closing Financing.

If the Combined Company is unable to realize the full strategic and financial benefits currently anticipated from the Merger, Cyclerion shareholders and Korsana stockholders will have experienced substantial dilution of their ownership interests without receiving any commensurate benefit, or only receiving part of the commensurate benefit to the extent the Combined Company is able to realize only part of the strategic and financial benefits currently anticipated from the Merger.

After the completion of the Merger, Cyclerion’s current shareholders will generally own a smaller percentage of the Combined Company than their ownership of Cyclerion prior to the Merger. Immediately after the Merger, Cyclerion securityholders as of immediately prior to the Merger are expected to own approximately 1.5% of the outstanding shares of capital stock of the Combined Company (on a fully-diluted basis), and former holders of Korsana securities are expected to own approximately 98.5% of the outstanding shares of capital stock of the Combined Company (on a fully-diluted basis), subject to certain assumptions, including, but not limited to, Cyclerion’s Net Cash as of closing being equal to $0. The Chief Executive Officer and President of Korsana will serve as the Chief Executive Officer and President of the Combined Company following the completion of the Merger.

While the Merger Agreement is in effect, each party is generally prohibited from, among other things, soliciting, initiating or knowingly encouraging, inducing or facilitating the communication, making, submission or announcement of any acquisition proposal or acquisition inquiry. In addition, Cyclerion’s current directors and executive officers have entered into support agreements pursuant to the terms of the Merger Agreement, and as an inducement to Korsana’s willingness to enter into the Merger Agreement, by which they have agreed to vote all of their shares of Cyclerion capital stock in favor of the Merger Agreement and the transactions contemplated thereby and against any competing proposals, subject to certain limited exceptions. These provisions could discourage a potential competing acquirer from considering or proposing an acquisition or merger, even if it were prepared to pay consideration with a higher value than that implied by the merger consideration in the combination.

Because the lack of a public market for Korsana Common Stock makes it difficult to evaluate the fair market value of its capital stock, the value of Cyclerion Common Stock to be issued to Korsana stockholders may be more or less than the fair market value of Korsana Common Stock.

The outstanding capital stock of Korsana is privately held and is not traded on any public market. The lack of a public market makes it difficult to determine the fair market value of Korsana capital stock. Because the percentage of Cyclerion’s equity to be issued to Korsana stockholders was determined based on negotiations between the parties, it is possible that the value of Cyclerion Common Stock and Cyclerion Series B Preferred Stock to be issued to Korsana stockholders will be more or less than the fair market value of Korsana capital stock.

Lawsuits may be filed against Cyclerion, Korsana, or any of the members of their respective boards of directors arising out of the Merger, which may delay or prevent the Merger.

Putative stockholder complaints, including stockholder class action complaints, and other complaints may be filed against Cyclerion, the Cyclerion Board, Korsana, the Korsana Board and others in connection with the transactions contemplated by the Merger Agreement. The outcome of litigation is uncertain, and Cyclerion or Korsana may not be successful in defending against any such future claims. Lawsuits that may be filed against Cyclerion, the Cyclerion Board, Korsana, or the Korsana Board could delay or prevent the Merger, divert the attention of Cyclerion’s and Korsana’s management and employees from their day-to-day business and otherwise adversely affect Cyclerion and Korsana financially.

Cyclerion has never paid and, other than in connection with the Merger, does not intend to pay any cash dividends in the foreseeable future.

Cyclerion has never paid cash dividends on any of its capital stock. Cyclerion does not currently anticipate declaring or paying cash dividends on its capital stock in the foreseeable future.

If Cyclerion does not successfully consummate the Merger or another strategic transaction, Cyclerion’s board of directors may decide to pursue a dissolution and liquidation of Cyclerion. In such an event, the amount of cash available for distribution to Cyclerion shareholders, if any, will depend heavily on the timing of such liquidation as well as the amount of cash that will need to be reserved for commitments and contingent liabilities, as to which Cyclerion can give you no assurance.

There can be no assurance that the Merger will be completed. If the Merger is not completed, Cyclerion’s board of directors may decide to pursue a dissolution and liquidation of Cyclerion. In such an event, the amount of cash available for distribution to Cyclerion shareholders, if any, will depend heavily on the timing of such decision and, ultimately, such liquidation, since the amount of cash available for distribution continues to decrease as Cyclerion funds its operations while pursuing the Merger. In addition, if Cyclerion’s board of directors were to approve and recommend, and Cyclerion shareholders were to approve, a dissolution and liquidation of Cyclerion,

Cyclerion would be required under Massachusetts law to pay Cyclerion’s outstanding obligations, as well as to make reasonable provision for contingent and unknown obligations, prior to making any distributions in liquidation to shareholders. Cyclerion’s commitments and contingent liabilities may include obligations under Cyclerion’s employment and related agreements with certain employees that provide for severance and other payments following a termination of employment occurring for various reasons, including a change in control of Cyclerion, litigation against Cyclerion, and other various claims and legal actions arising in the ordinary course of business, and other unexpected and/or contingent liabilities. As a result of this requirement, a portion of Cyclerion’s assets would need to be reserved pending the resolution of such obligations.

In addition, Cyclerion may be subject to litigation or other claims related to a dissolution and liquidation of Cyclerion. If a dissolution and liquidation were to be pursued, Cyclerion’s board of directors, in consultation with Cyclerion’s advisors, would need to evaluate these matters and make a determination about a reasonable amount to reserve. Accordingly, holders of Cyclerion Common Stock could lose all or a significant portion of their investment in the event of liquidation, dissolution or winding up of Cyclerion. A liquidation would be a lengthy and uncertain process with no assurance of any value ever being returned to Cyclerion shareholders.

Cyclerion and its shareholders will not have any right to make damage claims against Korsana for the breach of any representation, warranty or covenant made by Korsana in the Merger Agreement.

The Merger Agreement provides that all of the representations, warranties and covenants of the parties contained therein shall not survive the closing of the Merger, except for those covenants contained therein that by their terms apply or are to be performed in whole or in part after the Closing, and then only with respect to breaches occurring after the closing of the Merger. Accordingly, there are no remedies available to the parties with respect to any breach of the representations, warranties, covenants or agreements of the parties to the Merger Agreement after the Closing of the Merger, except for covenants to be performed in whole or in part after the Closing. As a result, Cyclerion and its shareholders will have no remedy available to them if the Merger is consummated and it is later revealed that there was a breach of any of the representations, warranties and covenants made by Korsana at the time of the Merger.

Additionally, Cyclerion cannot assure you that the due diligence conducted in relation to Korsana has identified all material issues or risks associated with Korsana, its business or the industry in which it competes. Furthermore, Cyclerion cannot assure you that factors outside of its or Korsana’s control will not later arise, or that any previously identified risks will not materialize in a manner inconsistent with the preliminary analysis. As a result of these factors, following the closing of the Merger, the Combined Company may be exposed to liabilities and incur additional costs and expenses and it may be forced to later write-down or write off assets, restructure its operations, or incur impairment or other charges. Cyclerion and its shareholders have no indemnification rights against Korsana or its stockholders under the Merger Agreement. Accordingly, any shareholders of Cyclerion that remain stockholders of the Combined Company following the Merger could suffer a reduction in the value of their securities. Such shareholders are unlikely to have a remedy for such reduction in value unless they are able to successfully claim that the reduction was due to the breach by Cyclerion’s directors or officers of a duty of care or other fiduciary duty owed to them, or if they are able to successfully bring a private claim under securities laws that the registration statement or proxy statement/prospectus relating to the Merger contained an actionable material misstatement or material omission.

Cyclerion’s shareholders potentially may not receive any payment on the CVRs and the CVRs may otherwise expire valueless.

The Merger Agreement contemplates that, at or prior to the First Effective Time, Cyclerion and the Rights Agent will execute and deliver the CVR Agreement, pursuant to which each person who was a shareholder of record of Cyclerion’s capital stock as of the close of business on the last business day prior to the day on which the First Effective Time occurs will be entitled to receive a CVR, issued by Cyclerion subject to and in accordance with the terms and conditions of the CVR Agreement. Pursuant to the CVR Agreement, each CVR holder is entitled to certain rights to receive a pro rata portion of the proceeds, if any, received by Cyclerion as a result of the disposition of Cyclerion’s pre-merger legacy assets during specified periods of time. Such proceeds are subject to certain permitted deductions. The right of Cyclerion’s shareholders to derive any value from the CVRs will be contingent solely upon the disposition of Cyclerion’s pre-merger legacy assets within the time periods specified in the CVR Agreement or any other contingencies as provided in the CVR Agreement.

Cyclerion may not be able to achieve successful results from the disposition of Cyclerion’s pre-merger legacy assets as described above. If this is not achieved for any reason within the time periods specified in the CVR Agreement, no payments will be made under the CVRs, and the CVRs will expire valueless.

The tax treatment of the CVRs is uncertain.

The Combined Company intends to treat the issuance of the CVRs to the persons who prior to completion of the Merger were Cyclerion shareholders as a distribution of property with respect to Cyclerion capital stock. However, the U.S. federal income tax treatment of the CVRs is uncertain. There is no legal authority directly addressing the U.S. federal income tax treatment of contingent value rights with characteristics similar to the CVRs. Therefore, it is possible that the issuance of the CVRs may be treated as a distribution of equity with respect to Cyclerion capital stock, as an “open transaction,” or as a “debt instrument” for U.S. federal income tax purposes, and such questions are inherently factual in nature.