Description of the Business

IGM Biosciences, Inc. (the Company) was incorporated in the state of Delaware in August 1993 under the name Palingen, Inc. and the name was subsequently changed to IGM Biosciences, Inc. in 2010.

The Company formerly had headquarters in Mountain View, California. In April and May 2025, the Company terminated all lease agreements and is currently a remote-only company and therefore does not have principal executive offices. Historically, IGM Biosciences, Inc. was a biotechnology company focused on the development of IgM antibodies for the treatment of cancer and autoimmune and inflammatory diseases.

Prior to September 30, 2024, the Company consolidated two wholly owned subsidiaries. To simplify the corporate structure, the Company’s board of directors approved the merger (Subsidiary Merger) of the subsidiaries with and into the Company, with the Company being the surviving corporation, effective August 30, 2024.

Because the Subsidiary Merger was a reorganization of entities under common control, the net assets were transferred from its subsidiaries at historical carrying value and the effects of the transaction were applied retrospectively as if the Subsidiary Merger had occurred at the earliest date presented in the Company’s financial statements in accordance with Accounting Standard Codification (ASC) Topic 250, Accounting changes and error corrections (Topic 250). The Subsidiary Merger did not have an impact on the financial statements as the Company's financials have historically been presented on a consolidated basis.

On July 1, 2025, the Company entered into an Agreement and Plan of Merger (the Merger Agreement) with Concentra Biosciences, LLC, a Delaware limited liability company (Concentra), and Concentra Merger Sub V, Inc, a Delaware corporation and a wholly owned subsidiary of Concentra (Merger Sub). The Merger Agreement provides for, among other things: (i) the acquisition of all of the Company’s outstanding shares of common stock, par value $0.01 per share (the Common Stock), by Concentra through a tender offer (the Offer), for a price per share of the Common Stock of (A) $1.247 in cash (the Cash Amount), subject to applicable tax withholding and without interest, plus (B) one contingent value right (a CVR) (such amount being the CVR Amount and the Cash Amount plus the CVR Amount, collectively being the Offer Price) and (ii) after completion of the Offer and subject to the satisfaction or waiver of certain conditions set forth in the Merger Agreement, the merger of Merger Sub into the Company (the Merger) with the Company surviving the Merger. If the Merger is effected, the Common Stock will be delisted from The Nasdaq Stock Market LLC and the Company’s obligation to file periodic reports under the Securities Act of 1934, as amended (the Exchange Act), will terminate, and the Company will be privately held. If the Merger is not completed and another strategic alternative is not identified, the Company’s Board of Directors may decide to pursue a dissolution or liquidation. There can be no assurance that the Merger will be completed as it is subject to various closing conditions. See Note 14 – Subsequent Events for additional information.

Basis of Presentation

The accompanying unaudited condensed financial statements have been prepared in accordance with accounting principles generally accepted in the United States (U.S. GAAP), as defined by the Financial Accounting Standards Board (FASB), and applicable rules and regulations of the Securities and Exchange Commission (SEC) regarding interim financial reporting. As permitted under those rules, certain footnotes or other financial information that are normally required by GAAP have been condensed or omitted, and accordingly the balance sheet as of December 31, 2024 has been derived from the audited financial statements at that date but does not include all of the information required by GAAP for complete financial statements. These unaudited interim condensed financial statements have been prepared on the same basis as the Company’s annual financial statements and, in the opinion of management, reflect all adjustments, consisting only of normal recurring adjustments which are necessary for a fair statement of the Company’s financial information. The interim results of operations for the three and six months ended June 30, 2025 are not necessarily indicative of the results to be expected for the year ending December 31, 2025 or for any other interim period or for any other future year.

The accompanying interim unaudited condensed financial statements should be read in conjunction with the audited financial statements and the related notes thereto for the year ended December 31, 2024, included in the Company’s Annual Report on Form 10-K filed with the SEC on March 6, 2025.

Liquidity

With the exception of the current period in which the Company recognized the remaining deferred revenue due to the termination of the collaboration agreement with Sanofi (see Note 7 – Sanofi Agreement for additional discussion on the agreement and termination), the Company has incurred net operating losses and negative cash flows from operations since its inception and had an accumulated deficit of $972.3 million as of June 30, 2025. As of June 30, 2025, the Company had cash, cash equivalents, and marketable securities of $104.3 million. Management believes that the existing financial resources are sufficient to continue operating activities at least one year past the issuance date of these condensed financial statements. The Company has historically financed its operations primarily

through the sale of common stock and pre-funded warrants in its public offerings and private placement, the sale of convertible preferred stock and issuance of unsecured promissory notes in private placements, and funding received from our collaboration partners. To date, none of the Company’s product candidates have been approved for sale, and the Company has not generated any product revenue since inception. Management expects expenses and operating losses to decrease for the foreseeable future, and the Company’s net losses may fluctuate significantly from period to period, depending on the outcome of the Merger and depending on whether the Company decides to pursue any future product development efforts if the Merger is not completed. The Company’s prospects are subject to risks, expenses and uncertainties frequently encountered by companies in the biotechnology industry as discussed below. While the Company has been able to raise multiple rounds of financing, there can be no assurance that in the event the Company requires additional financing, such financing will be available on terms which are favorable or at all. Failure to raise sufficient capital when needed or generate sufficient cash flow from operations would impact the ability to pursue business strategies and could require the Company to delay, scale back or discontinue one or more product development programs, or other aspects of the Company's business objectives. As discussed above and in Note 14 – Subsequent Events, the Company has entered into a Merger Agreement with Concentra and Merger Sub, which, if effected would result in the full termination of the Company's current and ongoing operations.