X0306 4 2021-03-02 0 0001419242 ATLANTIC POWER CORP AT 0001136877 MOORE JAMES J JR C/O ATLANTIC POWER CORPORATION 3 ALLIED DRIVE, SUITE 155 DEDHAM MA 02026 1 1 0 0 Chief Executive Officer Common shares 2021-03-02 4 M 0 53066 A 1232559 D Common shares 2021-03-02 4 F 0 42291 2.89 D 1232559 D Common shares 2021-03-02 4 M 0 39214 A 1232559 D Common shares 2021-03-02 4 F 0 31251 2.89 D 1232559 D Common shares 2021-03-02 4 M 0 38553 A 1232559 D Common shares 2021-03-02 4 F 0 30724 2.89 D 1232559 D Notional shares 2021-03-02 4 M 0 95357 2.89 D Common shares 95357 359020 D Notional shares 2021-03-02 4 M 0 70465 2.89 D Common shares 70465 359020 D Notional shares 2021-03-02 4 M 0 69277 2.89 D Common shares 69277 359020 D The reporting person acquired shares pursuant to the vesting (disclosed on Table II) of notional shares awarded in 2018. 55.65% of the vested notional shares were settled in common shares and 45.35% were settled in cash, which was deposited into the reporting persons applicable payroll tax withholding account. The reporting person acquired shares pursuant to the vesting (disclosed on Table II) of notional shares awarded in 2019. 55.65% of the vested notional shares were settled in common shares and 45.35% were settled in cash, which was deposited into the reporting persons applicable payroll tax withholding account. The reporting person acquired shares pursuant to the vesting (disclosed on Table II) of notional shares awarded in 2020. 55.65% of the vested notional shares were settled in common shares and 45.35% were settled in cash, which was deposited into the reporting persons applicable payroll tax withholding account. The reporting person vested in respect of one third of the notional shares granted in 2018. The reporting person vested in respect of one third of the notional shares granted in 2019. The reporting person vested in respect of one third of the notional shares granted in 2020. /s/ John S. Miele, attorney-in-fact 2021-03-04