An end effector for stapling tissue is disclosed. The end effector comprises a staple cartridge comprising staples removably stored therein and an anvil configured to deform the staples. The anvil comprises a proximal portion, a distal portion, and a middle portion intermediate the proximal portion and the distal portion, wherein one of the anvil and the staple cartridge is movable relative to the other one of the anvil and the staple cartridge between an open configuration and a closed configuration. The anvil and the staple cartridge are configured to hold the tissue therebetween in the closed configuration. The proximal portion and the distal portion of the anvil are closer to the staple cartridge than the middle portion in the closed configuration. The anvil is pivotally movable relative to the staple cartridge and the anvil is laterally and asymmetrically movable relative to the staple cartridge.
