Circle K Corp., which operates dozens of convenience stores in Utah, has signed a definitive purchase agreement with the Charter Co., meaning Circle K will acquire Charter subsidiaries. Charter operates 538 gasoline and convenience stores in 13 southern and northeastern states.

Subject to corporate and regulatory approval, the agreement calls for $50 million in new issue of Circle K convertible preferred stock and $70 million in cash.

When the transaction is completed, Circle K will operate 4,585 convenience stores in 31 states, including Michigan, Maine, New Hampshire, Connecticut and Massachusetts, which will be new states for Circle K operation.