Zions Bancorp announced another bank acquisition Thursday: Commerce Bancorp based in Seattle, whose principal subsidiary is The Commerce Bank of Washington, N.A.

The deal calls for Commerce to merge into Zions in exchange for an unspecified number of shares of Zions' stock. Terms were not disclosed. Commerce operates a single office in Seattle. The merger is structured to be tax-free and will be accounted for as a pooling of interests. Zions said it will incur some $2 million in after-tax charges relating to the merger.