| Date | Name | Symbol | Type | Security | Shares | Price | Value | Ownership | Reported |
| 01/17/2023 | Mersana Therapeutics, Inc. | MRSN | Sale | Common Stock | 3.6k | $5.74 | $20.5k | | 01/13/2023 |
| 01/15/2023 | Mersana Therapeutics, Inc. | MRSN | Exercise | Restricted stock unit | 833 | $0.00 | $0 | | 01/13/2023 |
| 01/15/2023 | Mersana Therapeutics, Inc. | MRSN | Exercise | Restricted stock unit | 4.5k | $0.00 | $0 | | 01/13/2023 |
| 01/14/2023 | Mersana Therapeutics, Inc. | MRSN | Exercise | Restricted stock unit | 4.8k | $0.00 | $0 | | 01/13/2023 |
| 01/13/2023 | Mersana Therapeutics, Inc. | MRSN | Grant | Restricted stock unit | 10.6k | $0.00 | $0 | | 01/13/2023 |
| 01/13/2023 | Mersana Therapeutics, Inc. | MRSN | Grant | Stock option (right to buy) | 47.6k | $6.06 | $288.6k | | 01/13/2023 |
| 01/18/2022 | Mersana Therapeutics, Inc. | MRSN | Sale | Common Stock | 2k | $5.92 | $11.7k | | 01/14/2022 |
| 01/14/2022 | Mersana Therapeutics, Inc. | MRSN | Exercise | Restricted Stock Units | 833 | $0.00 | $0 | | 01/14/2022 |
| 01/14/2022 | Mersana Therapeutics, Inc. | MRSN | Exercise | Restricted Stock Units | 4.5k | $0.00 | $0 | | 01/14/2022 |
| 01/14/2022 | Mersana Therapeutics, Inc. | MRSN | Grant | Stock Option (right to buy) | 28.7k | $6.28 | $180.2k | | 01/14/2022 |
| 01/14/2022 | Mersana Therapeutics, Inc. | MRSN | Grant | Restricted Stock Units | 19.1k | $0.00 | $0 | | 01/14/2022 |
| 01/19/2021 | Mersana Therapeutics, Inc. | MRSN | Sale | Common Stock | 545 | $21.28 | $11.6k | | 01/15/2021 |
| 01/15/2021 | Mersana Therapeutics, Inc. | MRSN | Payment of Exercise | Common Stock | 289 | $21.09 | $6.1k | | 01/15/2021 |
| 01/15/2021 | Mersana Therapeutics, Inc. | MRSN | Exercise | Restricted Stock Units | 834 | $0.00 | $0 | | 01/15/2021 |
| 01/15/2021 | Mersana Therapeutics, Inc. | MRSN | Grant | Restricted Stock Units | 18.1k | $0.00 | $0 | | 01/15/2021 |
| 01/15/2021 | Mersana Therapeutics, Inc. | MRSN | Grant | Stock Option (right to buy) | 27.1k | $21.09 | $571.9k | | 01/15/2021 |
| 01/04/2021 | Mersana Therapeutics, Inc. | MRSN | Sale | Common Stock | 247 | $26.76 | $6.6k | | 01/04/2021 |
| 07/02/2020 | Mersana Therapeutics, Inc. | MRSN | Sale | Common Stock | 3.4k | $22.49 | $76.1k | | 07/02/2020 |
| 06/30/2020 | Mersana Therapeutics, Inc. | MRSN | Purchase | Common Stock | 3.4k | $4.87 | $16.5k | | 07/02/2020 |
| 01/15/2020 | Mersana Therapeutics, Inc. | MRSN | Grant | Stock Option (right to buy) | 15k | $6.16 | $92.4k | | 01/15/2020 |
| 01/15/2020 | Mersana Therapeutics, Inc. | MRSN | Grant | Restricted Stock Units | 3.3k | $0.00 | $0 | | 01/15/2020 |