# EDGAR Filing Document

**Accession Number:** 0001496323
**File Stem:** 0001140361-25-031226
**Filing Date:** 2025-8
**Character Count:** 10053
**Document Hash:** 2f2bf00aa2c3ec2f1eb301ec5a449641
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001140361-25-031226.hdr.sgml**: 20250814

**ACCESSION NUMBER**: 0001140361-25-031226

**CONFORMED SUBMISSION TYPE**: S-8 POS

**PUBLIC DOCUMENT COUNT**: 1

**FILED AS OF DATE**: 20250814

**DATE AS OF CHANGE**: 20250814

**EFFECTIVENESS DATE**: 20250814

**FILER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** IGM Biosciences, Inc.
- **CENTRAL INDEX KEY:** 0001496323
- **STANDARD INDUSTRIAL CLASSIFICATION:** PHARMACEUTICAL PREPARATIONS [2834]
- **ORGANIZATION NAME:** 03 Life Sciences
- **EIN:** 770349194
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** S-8 POS
- **SEC ACT:** 1933 Act
- **SEC FILE NUMBER:** 333-233826
- **FILM NUMBER:** 251218963

**BUSINESS ADDRESS:**
- **STREET 1:** 325 E MIDDLEFIELD ROAD
- **CITY:** MOUNTAIN VIEW
- **STATE:** CA
- **ZIP:** 94043
- **BUSINESS PHONE:** 650-965-7873

**MAIL ADDRESS:**
- **STREET 1:** 325 E MIDDLEFIELD ROAD
- **CITY:** MOUNTAIN VIEW
- **STATE:** CA
- **ZIP:** 94043

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** Palingen, Inc.
- **DATE OF NAME CHANGE:** 20100712

#### As filed with the Securities and Exchange Commission on August 14, 2025

#### Registration No. 333-233826

#### Registration No. 333-237411

#### Registration No. 333-248111

#### Registration No. 333-254877
**Registration No. 333-263927**

**Registration No. 333-270991**

**Registration No. 333-277744**

**Registration No. 333-285602**

#### UNITED STATES

### SECURITIES AND EXCHANGE COMMISSION

#### Washington, D.C. 20549

#### <br>

#### POST-EFFECTIVE AMENDMENT NO. 1 TO FORM S-8 REGISTRATION STATEMENT NO. 333-233826

#### POST-EFFECTIVE AMENDMENT NO. 1 TO FORM S-8 REGISTRATION STATEMENT NO. 333-237411

#### POST-EFFECTIVE AMENDMENT NO. 1 TO FORM S-8 REGISTRATION STATEMENT NO. 333-248111

#### POST-EFFECTIVE AMENDMENT NO. 1 TO FORM S-8 REGISTRATION STATEMENT NO. 333-254877

#### POST-EFFECTIVE AMENDMENT NO. 1 TO FORM S-8 REGISTRATION STATEMENT NO. 333-263927

#### POST-EFFECTIVE AMENDMENT NO. 1 TO FORM S-8 REGISTRATION STATEMENT NO. 333-270991

#### POST-EFFECTIVE AMENDMENT NO. 1 TO FORM S-8 REGISTRATION STATEMENT NO. 333-277744

#### POST-EFFECTIVE AMENDMENT NO. 1 TO FORM S-8 REGISTRATION STATEMENT NO. 333-285602

### FORM S-8

#### REGISTRATION STATEMENT

#### UNDER

#### THE SECURITIES ACT OF 1933

#### <br>

## IGM BIOSCIENCES, INC.

#### (Exact name of registrant as specified in its charter)

#### <br>

---

| | |
|:---|:---|
| **Delaware** | **77-0349194** |
| **(State or other jurisdiction of**<br> **incorporation or organization)** | **(IRS employer**<br> **identification number)** |

---

#### 4747 Executive Drive, Suite 210

#### San Diego, California 92121

#### (Address of Principal Executive Offices, including Zip Code)

#### <br>

#### Amended and Restated 2018 Omnibus Incentive Plan

#### Amended and Restated 2019 Employee Stock Purchase Plan

#### Amended and Restated 2010 Stock Plan

#### (Full title of the Plans)

#### <br>

#### Michael Hearne

#### Chief Financial Officer

#### IGM Biosciences, Inc.

#### 4747 Executive Drive, Suite 210

#### San Diego, California 92121
(858) 281-5372

#### (Name, Address and Telephone Number, including Area Code, of Agent for Service)

#### Copies to :

#### Ryan A. Murr

#### Gibson, Dunn & Crutcher LLP

#### One Embarcadero Center Suite 2600

#### San Francisco, California 94111
(415) 393-8200

#### Tony Jeffries

#### Robert T. Ishii

#### Jennifer Knapp

#### Ethan Lutske

#### Wilson Sonsini Goodrich & Rosati, P.C.

#### 650 Page Mill Road

#### Palo Alto, California 94304
(650) 493-9300

#### <br>

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See definitions of "large accelerated filer, "accelerated filer," "smaller reporting company," and "emerging growth company" in Rule 12b-2 of the Exchange Act.

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| | | | |
|:---|:---|:---|:---|
| Large accelerated filer | ☐ | Accelerated filer | ☐ |
| Non-accelerated filer | ☒ | Smaller reporting company | ☒ |
|  |  | Emerging growth company | ☐ |

---

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 7(a)(2)(B) of the Securities Act. ☐

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#### EXPLANATORY NOTE

#### DEREGISTRATION OF UNSOLD SECURITIES

These Post-Effective Amendments (the "<u>Post-Effective Amendments</u>") filed by IGM Biosciences, Inc., a Delaware corporation (the "<u>Registrant</u>"), to deregister all shares of the Registrant's common stock, $0.01 par value per share (the "<u>Shares</u>"), remaining unissued under the following Registration Statements on Form S-8 (each, a "<u>Registration Statement</u>", and collectively, the "<u>Registration Statements</u>") filed by the Registrant with the U.S. Securities and Exchange Commission (the "<u>Commission</u>").

• Registration Statement on Form S-8 (No. [333-233826](https://www.sec.gov/Archives/edgar/data/1496323/000119312519248374/d786934ds8.htm)) pertaining to the registration of (i) 4,372,807 Shares issuable under the Amended and Restated 2018 Omnibus Incentive Plan (the "<u>2018 Plan</u>"), (ii) 280,000 Shares issuable under the Amended and Restated 2019 Employee Stock Purchase Plan (the "<u>ESPP</u>") and (iii) 595,832 Shares issuable under the Amended and Restated 2010 Stock Plan.

• Registration Statement on Form S-8 (No. [333-237411](https://www.sec.gov/Archives/edgar/data/1496323/000119312520087043/d908460ds8.htm)) pertaining to the registration of (i) 964,487 Shares issuable under the 2018 Plan and (ii) 241,121 Shares issuable under the ESPP.

• Registration Statement on Form S-8 (No. [333-248111](https://www.sec.gov/Archives/edgar/data/1496323/000119312520223697/d68587ds8.htm)) pertaining to the registration of (i) 257,248 Shares issuable under the 2018 Plan and (ii) 64,312 Shares issuable under the ESPP.

• Registration Statement on Form S-8 (No. [333-254877](https://www.sec.gov/Archives/edgar/data/1496323/000119312521100614/d150442ds8.htm)) pertaining to the registration of (i) 1,278,965 Shares issuable under the 2018 Plan and (ii) 319,741 Shares issuable under the ESPP.

• Registration Statement on Form S-8 (No. [333-263927](https://www.sec.gov/Archives/edgar/data/1496323/000119312522087415/d305141ds8.htm)) pertaining to the registration of (i) 1,299,920 Shares issuable under the 2018 Plan and (ii) 324,980 Shares issuable under the ESPP.

• Registration Statement on Form S-8 (No. [333-270991](https://www.sec.gov/Archives/edgar/data/1496323/000095017023010936/igm_s8_2023.htm)) pertaining to the registration of (i) 1,723,292 Shares issuable under the 2018 Plan and (ii) 430,823 Shares issuable under the ESPP.

• Registration Statement on Form S-8 (No. [333-277744](https://www.sec.gov/Archives/edgar/data/1496323/000095017024027999/igm_s8_2024.htm)) pertaining to the registration of (i) 4,507,245 Shares issuable under the 2018 Plan and (ii) 560,000 Shares issuable under the ESPP.

• Registration Statement on Form S-8 (No. [333-285602](https://www.sec.gov/Archives/edgar/data/1496323/000095017025034760/igm_s8_2025.htm)) pertaining to the registration of (i) 2,385,497 Shares issuable under the 2018 Plan and (ii) 560,000 Shares issuable under the ESPP.

The Registrant is filing these Post-Effective Amendments to withdraw and remove any unissued and unsold securities issuable by Registration pursuant to the above-referenced Registration Statements.

On July 1, 2025, the Registrant entered into an Agreement and Plan of Merger (the "<u>Merger Agreement</u>") with Concentra Biosciences, LLC, a Delaware limited liability company ("<u>Parent</u>"), and Concentra Merger Sub V, Inc., a Delaware corporation and wholly owned subsidiary of Parent ("<u>Merger Sub</u>"). Pursuant to the Merger Agreement, on August 14, 2025, Merger Sub was merged with and into the Registrant with the Registrant surviving as a wholly owned subsidiary of Parent (the "<u>Merger</u>"). In the Merger, each share of Common Stock (the "<u>Shares</u>") (other than (i) Shares owned or held in the Company's treasury immediately prior to the Effective Time, (ii) Shares owned directly or indirectly by Parent or Merger Sub immediately prior to the Effective Time and (iii) Shares held by any stockholder of the Registrant who properly exercised appraisal rights under Delaware law) was converted into the right to receive (i) $1.247 per Share in cash and (ii) one non-transferable contractual contingent value right for each Share.

As a result of the Merger, the Registrant has terminated all offerings of its securities pursuant to the Registration Statements. In accordance with an undertaking made by the Registrant in each of the Registration Statements to remove from registration, by means of a post-effective amendment, any of the securities that had been registered for issuance that remain unsold at the termination of the offerings, the Registrant hereby removes from registration all such securities registered under the Registration Statements that remain unsold as of the date hereof and terminates the effectiveness of the Registration Statements.

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#### SIGNATURE

Pursuant to the requirements of the Securities Act of 1933, the Registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-8 and has duly caused these Post-Effective Amendments to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of San Diego, State of California, on August 14, 2025. No other person is required to sign these Post-Effective Amendment to the Registration Statements in reliance on Rule 478 of the Securities Act of 1933, as amended.

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| |
|:---|
| **IGM BIOSCIENCES, INC.** |
|  By: /s/ Michael Hearne |
|  Name: Michael Hearne<br> Title: Chief Financial Officer |

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