Mangrove Partnerslowered its stake in Atlantic PowerCorp. to 6,513,514 shares representing 5.4% ownership, according toan amended Schedule 13D filed April 7.

The investment group and its related vehicles beneficially owned8,184,331 shares, or 6.73% of the company, at the end of the first quarter, SNLEnergy datashows.

12 West CapitalManagement LP is now the largest institutional owner in the companyat a position of 7,308,076 shares representing 6.01% of the company.