Oregon-based Pacific Continental has agreed to merge with Washington-based Columbia Banking System in a deal worth about $644.1m.

The merged entity will have over 150 branches across Washington, Oregon and Idaho, and will manage nearly $12bn in assets.

Under the arrangement, shareholders of Pacific Continental will get 0.6430 of a share of Columbia common stock for each share of Pacific Continental stock.

The deal already secured the approval of the board of directors of both companies. It is expected to be completed in mid-2017, subject to shareholder and regulatory approvals.

Shareholders of Pacific Continental shareholders will own about 20% of the merged group following deal closing. 

Columbia CEO and president Melanie Dressel said: “This merger exceeds our financial metrics with double digit earnings accretion and a tangible book value earnback of 3.7 years.  We look forward to continuing Pacific Continental's leadership position in the Eugene market while enhancing our presence in the Portland and Seattle markets with the help of Pacific Continental's key niche practice and market leaders.

“Additionally, at closing, one current community-based director from Pacific Continental's Board of Directors will join the Board of Columbia."