Circle K Corp., a large convenience store...

Circle K Corp., a large convenience store operator, said it has hired an investment banker to explore options to enhance shareholders’ value--news that caused the company’s shares to rise sharply. The Phoenix-based company said it hired Wasserstein, Perella & Co. to look into such options as an expansion, restructuring, recapitalization, a merger or joint venture. Circle K’s shares closed up $2.25 at $14.75 on the New York Stock Exchange.