| Date | Name | Symbol | Type | Security | Shares | Price | Value | Ownership | Reported |
| 01/17/2023 | Mersana Therapeutics, Inc. | MRSN | Sale | Common Stock | 5.1k | $5.74 | $29.5k | | 01/13/2023 |
| 01/15/2023 | Mersana Therapeutics, Inc. | MRSN | Exercise | Restricted stock unit | 4k | $0.00 | $0 | | 01/13/2023 |
| 01/15/2023 | Mersana Therapeutics, Inc. | MRSN | Exercise | Restricted stock unit | 6.2k | $0.00 | $0 | | 01/13/2023 |
| 01/14/2023 | Mersana Therapeutics, Inc. | MRSN | Exercise | Restricted stock unit | 6.2k | $0.00 | $0 | | 01/13/2023 |
| 01/13/2023 | Mersana Therapeutics, Inc. | MRSN | Grant | Restricted stock unit | 40k | $0.00 | $0 | | 01/13/2023 |
| 01/13/2023 | Mersana Therapeutics, Inc. | MRSN | Grant | Stock option (right to buy) | 180k | $6.06 | $1.1M | | 01/13/2023 |
| 01/14/2022 | Mersana Therapeutics, Inc. | MRSN | Grant | Restricted Stock Units | 25k | $0.00 | $0 | | 01/14/2022 |
| 01/14/2022 | Mersana Therapeutics, Inc. | MRSN | Grant | Stock Option (right to buy) | 112.5k | $6.28 | $706.5k | | 01/14/2022 |
| 01/14/2022 | Mersana Therapeutics, Inc. | MRSN | Exercise | Restricted Stock Units | 6.2k | $0.00 | $0 | | 01/14/2022 |
| 01/14/2022 | Mersana Therapeutics, Inc. | MRSN | Exercise | Restricted Stock Units | 4k | $0.00 | $0 | | 01/14/2022 |
| 01/15/2021 | Mersana Therapeutics, Inc. | MRSN | Payment of Exercise | Common Stock | 1.2k | $21.09 | $24.5k | | 01/15/2021 |
| 01/15/2021 | Mersana Therapeutics, Inc. | MRSN | Exercise | Restricted Stock Units | 4k | $0.00 | $0 | | 01/15/2021 |
| 01/15/2021 | Mersana Therapeutics, Inc. | MRSN | Grant | Stock Option (right to buy) | 112.5k | $21.09 | $2.4M | | 01/15/2021 |
| 01/15/2021 | Mersana Therapeutics, Inc. | MRSN | Grant | Restricted Stock Units | 25k | $0.00 | $0 | | 01/15/2021 |
| 01/15/2020 | Mersana Therapeutics, Inc. | MRSN | Grant | Stock Option (right to buy) | 71.2k | $6.16 | $438.9k | | 01/15/2020 |
| 01/15/2020 | Mersana Therapeutics, Inc. | MRSN | Grant | Restricted Stock Units | 15.8k | $0.00 | $0 | | 01/15/2020 |
| 07/10/2019 | Mersana Therapeutics, Inc. | MRSN | Grant | Stock Option (right to buy) | 240k | $3.99 | $957.6k | | 07/10/2019 |