| Id | Content |
|---|---|
| F1 | The shares were acquired under the IGM Biosciences, Inc. 2019 Employee Stock Purchase Plan in a transaction that was exempt under both Rule 16b-3(d) and Rule 16b-3(c). |
| F2 | These shares were sold to cover tax withholding obligations in connection with the vesting of restricted stock units. |
| F3 | This transaction was executed in multiple trades at prices ranging from $7.26 to $7.94. The price reported above reflects the weighted average sale price. The Reporting Person undertakes to provide upon request by the staff of the Securities and Exchange Commission, the Issuer, or a security holder of the Issuer, full information regarding the number of shares sold at each separate sale price. |
| F4 | The shares are held directly by the Reporting Person's spouse. |