San Luis Obispo-based American Perspective Bank is being purchased by Portland-based Umpqua Holdings Corp. for $44.7 million.

Under the deal, announced April 10, Umpqua will pay $10 per share in cash for American Perspective. The San Luis Obispo bank’s three Central Coast branches will be rebranded as Umpqua Bank.

The acquisition has been approved by the boards of both companies but is still subject to regulatory and shareholder approval. The deal is expected to close mid-2012, they said, with the operational integration of the banks completed during the second half of the year. In a message to customers, American Perspective said Umpqua “has a history of taking care of associates during times of change, and we will work hard to limit the number of positions affected by this transition.”

The combined bank would have assets of about $11.8 billion.

“This merger provides us with the opportunity to expand our presence in California in partnership with a terrific organization and we look forward to becoming an integral part of the Central Coast community,” Umpqua Bank President and CEO Ray Davis said in a news release.

American Perspective Bank, formerly American Principle Bank, was founded in 2007. It is one of the mid-sized banks in the region, ranking at No. 6 on the list of banks based in the Tri-Counties with $255.3 million in assets as of the third quarter of 2011. It has three branches, in San Luis Obispo, Santa Maria and Paso Robles. Publicly traded on the over-the-counter bulletin board, American Perspective has a market capitalization of about $42 million.

Umpqua has 196 branches in Oregon, Washington, Northern California and Northern Nevada.

Shares of American Perspective shot up 10.1 percent to $9.80 in mid-morning trading after the announcement. Umpqua Holdings shares were down 0.6 percent to $12.76.