Common Stock

At the Company's annual meeting of stockholder on May 19, 2026, the Company's stockholders approved and increase in the number of authorized shares of common stock, par value $0.001 per share from 115,000,000 shares to 215,000,000 shares. As of June 30, 2026, the Company’s Ninth Amended and Restated Certificate of Incorporation, as amended, authorized the Company to issue up to 215,000,000 shares of common stock, par value

$0.001 per share, of which 103,882,937 shares were issued and outstanding, and up to 5,000,000 shares of undesignated preferred stock, par value $0.001 per share, of which 500,000 shares were issued and outstanding.

The voting, dividend and liquidation rights of the holders of the Company’s common stock are subject to and qualified by the rights, powers and preferences of the holders of the preferred stock. Each share of common stock entitles the holder to one vote on all matters submitted to a vote of the Company’s stockholders. Common stockholders are entitled to receive dividends, as may be declared by the board of directors of the Company (the “Board”), if any. No cash dividends have been declared or paid to date.

In July 2025, the Company sold 21,562,500 shares of its common stock in an underwritten public offering at a price of $3.20 per share and received net proceeds of approximately $65.0 million.

In February 2026, the Company sold 23,000,000 shares of its common stock in an underwritten public offering at a price of $5.00 per share and received net proceeds of approximately $107.6 million.

ATM Agreement

In May 2024, the Company entered into a sales agreement (the "ATM Agreement") with Guggenheim Securities, LLC in connection with the establishment of an “at-the-market” offering program under which the Company could sell up to an aggregate of $100 million of shares of common stock (the “ATM Shares”) from time to time. To date, no sales of common stock have been made under this ATM Agreement.

Preferred Stock

In December 2025, the Company entered into an exchange agreement (the “Exchange Agreement”) with Blue Owl Healthcare Opportunities IV Public Investments LP (the “Stockholder”) pursuant to which the Stockholder exchanged 2,500,000 shares of the Company’s common stock for 250,000 shares of newly designated Series A Convertible Preferred Stock of par value $0.001 per share (the “Series A Preferred Stock”). In January 2026, the Stockholder exchanged an additional 2,500,000 shares of the Company’s common stock for an additional 250,000 shares of Series A Preferred Stock.

Each share of the Series A Preferred Stock will be convertible into ten shares of common stock at the option of the holder at any time, subject to certain limitations, including that the holder will be prohibited from converting preferred stock into common stock if, as a result of such conversion, the holder, together with its affiliates, would beneficially own a number of shares of common stock more than 9.99% of the total common stock then issued and outstanding immediately following the conversion of such shares of Series A Preferred Stock. Holders of the Series A Preferred Stock are permitted to increase this percentage to an amount not to exceed 19.99% upon 60 days’ notice.

Shares of Series A Preferred Stock will generally have no voting rights, except as required by law and except that the consent of a majority of the holders of the outstanding Series A Preferred Stock will be required to amend the terms of the preferred stock. In the event of the Company’s liquidation, dissolution or winding up, holders of Series A Preferred Stock will participate pari passu with any distribution of proceeds to holders of common stock, calculated on an as-converted basis. Holders of preferred stock are entitled to receive when, as, and if dividends are declared and paid on the common stock, an equivalent dividend, calculated on an as-converted basis. Shares of Series A Preferred Stock are otherwise not entitled to dividends.

The Series A Preferred Stock ranks on parity with the common stock and any class or series of capital stock of the Company created specifically ranking by its terms on parity with the preferred stock. Additionally, it ranks senior to any class or series of capital stock of the Company hereafter created specifically ranking by its terms junior to the preferred stock and junior to any class or series of capital stock of Larimar created specifically ranking by its terms senior to any preferred stock, in each case, as to distributions of assets upon liquidation, dissolution or winding up of the Company, whether voluntarily or involuntarily.

2020 Equity Incentive Plan

The Board adopted the 2020 Equity Incentive Plan (the“2020 Plan”) on July 16, 2020 and the stockholders of the Company approved the 2020 Plan on September 29, 2020. The 2020 Plan replaced the predecessor plans (the (“Prior Plans”) that the Company assumed following its merger with Zafgen in May 2020. Options outstanding under the Prior Plans will remain outstanding, unchanged, and subject to the terms of the Prior Plans and the respective award agreements, and no further awards will be made under the Prior Plans. However, if any award previously granted under the Prior Plans, expires, terminates, is canceled, or is forfeited for any reason after the

approval of the 2020 Plan, the shares subject to that award will be added to the 2020 Plan share pool so that they can be utilized for new grants under the 2020 Plan.

The 2020 Plan provides for the grant of incentive stock options (“ISOs”), nonstatutory stock options (“NSOs”), stock appreciation rights, restricted stock awards, restricted stock unit awards, performance-based restricted stock units, and cash or other stock-based awards. ISOs may be granted only to the Company’s employees, including the Company’s officers, and the employees of the Company’s affiliates. All other awards may be granted to the Company’s employees, including the Company’s officers, the Company’s non-employee directors and consultants, and the employees and consultants of the Company’s affiliates.

The maximum number of shares that may be issued in respect of any awards under the 2020 Plan is the sum of: (i) 1,700,000 shares plus (ii) an annual increase on January 1, 2021 and each anniversary of such date thereafter through January 1, 2030, equal to the lesser of (A) 4% of the shares issued and outstanding on the last day of the immediately preceding fiscal year, or (B) such smaller number of shares as determined by the Board (collectively, the “Plan Limit”). The maximum aggregate number of shares that may be issued under the 2020 Plan in respect of incentive stock options is 8,000,000 over the ten-year term of the 2020 Plan.

As permitted by the 2020 Plan, the Company added 3,323,616 and 2,552,603 shares available for grant to the 2020 Plan on January 1, 2026 and January 1, 2025, respectively. As of June 30, 2026, 848,841 shares of common stock were available for grant under the 2020 Plan.

During the six months ended June 30, 2026 and twelve months ended December 31, 2025, options to purchase 1,623 and 1,333 shares, respectively, issued under the Prior Plans were cancelled and became available for grant under the 2020 Plan.

Stock Option Valuation

Stock Options

Option Grants

During the six months ended June 30, 2026, the Company granted options to purchase 2,636,040 shares of common stock to employees and directors under the 2020 Plan. The options have an exercise price equal to the closing stock price as of the grant date. Of the 2,636,040 options granted, 2,360,290 were granted to employees and vest over four years, with 25% vesting on the first anniversary of the grant and the remainder vesting in equal monthly installments thereafter. The remaining 275,750 options were annual grants to the Company's directors and vest on the earlier of (i) one year from the grant date or (ii) the date of the Company's next annual meeting of stockholders. The weighted-average grant date fair value of options granted under the 2020 Plan during the six months ended June 30, 2026 was $2.87.

As of June 30, 2026, total unrecognized compensation expense related to unvested stock options granted under the 2020 Plan was $14.7 million, which is expected to be recognized over a weighted average period of 2.40 years.

Inducement Stock Option Grant

There were no inducement awards granted in the six months ended June 30, 2026.

As of June 30, 2026, total unrecognized compensation expense related to unvested inducement options granted was $0.2 million, which is expected to be recognized over a weighted average period of 0.82 years.

Restricted Stock Units

RSUs are granted under the 2020 Plan to certain of the Company's employees in order to retain key employees. The value of an RSU award is based on the Company's stock price on the date of grant. The shares underlying the RSUs are not issued until the RSUs vest.

Restricted Stock Unit Grants

During the six months ended June 30, 2026, the Company granted 527,190 shares of RSUs to employees under the 2020 Plan. The RSUs vest annually over four years and have a weighted-average grant date fair value of $3.60 per unit.

As of June 30, 2026, total unrecognized compensation expense for RSUs was $3.2 million, which is expected to be recognized over a weighted average period of 2.70 years.

Performance-Based Restricted Stock Unit Grants

In January 2025, the Company granted performance-based RSUs (the “January 2025 PSU Awards”) to each of the four executive officers of the Company under the 2020 Plan. Each award was expressed as a target number of RSUs. With respect to the January 2025 PSU Awards, the Board established specified regulatory-related performance criteria and a corresponding performance period over which such performance criteria must be achieved, the satisfaction of which are conditions to earning the January 2025 PSU Awards and vesting of the underlying RSUs. As of June 30, 2026, the January 2025 PSU Awards were outstanding covering 200,000 common stock underlying RSUs.

The grant date fair value of the performance-based RSUs was $3.46 per unit based on the grant date closing price per share. As of June 30, 2026, the underlying performance criteria of the January 2025 PSU Awards were determined to be not probable of achievement for accounting purposes, and no stock-based compensation expense was recognized for the three and six months ended June 30, 2026 and 2025.

Stock-Based Compensation