Sterling Savings Bank has entered into an agreement to acquire the Seattle-area operations of Boston Private Bank & Trust Company, which includes an office in Redmond.

The transaction, which has been approved by the boards of directors of Sterling and Boston Private, will enhance Sterling’s presence in the Puget Sound area, a priority market for Sterling.

“This transaction is in perfect alignment with our strategic focus on building out our commercial banking presence in key West Coast metropolitan areas,” said Sterling President and CEO Greg Seibly. “Boston Private’s Pacific Northwest operations include both a high-quality, relationship-based loan portfolio and a core deposit base composed almost entirely of transaction accounts. We expect that this acquisition will serve as a growth platform for Sterling, both through deepening and expanding our existing relationships and through adding new client relationships built by the Boston Private offices and staff.”

Other Boston Private Puget Sound offices are located in Seattle and Bellevue. As of Sept. 30, these offices and the Redmond location had aggregate loans of approximately $270 million and deposits of $190 million. Sterling will pay Boston Private a franchise premium of $11 million in addition to the net acquired asset value as consideration for the transaction.

The transaction, which is subject to regulatory approval and other customary conditions of closing, is expected to be completed during the first half of 2013. Upon completion of the acquisition, all three of Boston Private’s Seattle-area offices will operate under the Sterling Bank name. The three locations will become part of Sterling Bank’s branch network of locations throughout Washington, Oregon, Idaho and California.