Spokane-based AmericanWest Bank is acquiring Security Business Bank of San Diego, AmericanWest said in a news release this morning. AmericanWest is expecting to pay $26 million for the San Diego bank under the terms of the transaction, which still must be approved by regulators. “Security Business Bank is a very healthy, successful bank so we’ll make a good pair,” AmericanWest spokeswoman Kelly McPhee in an e-mail. “It gives them higher lending limits and more room to grow by partnering with us and it gives us more locations in the San Diego region — adding to the four we already have there.” AmericanWest operates more than 70 branches in Washington, Idaho, Utah and California, the bank said in the news release. Security Business Bank operates four branches in the San Diego area. The Spokane bank had assets of $2.3 billion and deposits of $2 billion on Dec. 31; Security Business Bank had assets of $233 million and deposits of $181 million as of that date.