Opus Bank, which has its executive headquarters in Irvine, said Monday it entered an agreement to buy Fullerton Community Bank.

Under the deal, Opus will pay $50 million in cash to common stock holders of RMG Capital Corp., the parent company of Fullerton Community. The transaction values each share at $17.47, a 1.32 multiple of RMG’s book value through March.

The boards of RMG, Fullerton and Opus banks have unanimously approved the deal.

The acquisition, subject to customary closing conditions, is expected to close in the fourth quarter.

Established in 1927, Fullerton Community is a federally chartered savings bank with about $682 million in assets, $511 million in deposits, and $530 million in loans.

It has eight branches in Anaheim, Brea, Fullerton, Garden Grove and Yorba Linda and is traded on the low-profile Pink Sheets.

Opus made a splash last year when Stephen Gordon, a veteran local banker, led a $460 million recapitalization of what had been known as Bay Cities National Bank.

Gordon has laid out a plan to grow Opus, which has its on-the-books headquarters in Redondo Beach, to 75 branches across California and more in Washington and Oregon.

In March Opus announced its first acquisition outside Southern California as it seeks to become a regional player along the West Coast. Its pending $21.7 million buy of Washington’s Cascade Financial and Cascade Bank includes 22 branches in the Seattle area and $1.5 billion in assets.

Last month the Business Journal reported that it finalized leases for six additional branches in Orange County and the rest of Southern California.

In addition to the six added branches, the bank said it has signed or is in the process of negotiating letters of intent for 11 other branches, including its first in the San Francisco area and other markets in Northern California.

Opus now has five branches in the South Bay area of Los Angeles County with one under way in Newport Beach set to open in August.

The bank now has about $700 million in assets and nearly $300 million in deposits.

After the acquisitions of Cascade Bank and RMG close, Opus is projected to have nearly $3 billion in assets and operate 42 branches on the West Coast.