Opus Bank became the largest Orange County-based commercial bank with a recent move of its headquarters to Irvine.

Opus had been officially based in Redondo Beach, with executive offices in Irvine, for the past year.

The bank has assets of about $2.2 billion.

The next-largest locally based commercial bank is Pacific Mercantile Bank in Costa Mesa, with nearly $1 billion in assets.

Opus Bank completed a $460 million recapitalization of Bay Cities National Bank a year ago, when it changed its name. The bank had five offices and about $280 million of assets at the time, according to Opus Chief Executive Stephen Gordon.

The bank has grown to 29 offices through acquisitions and new openings in the last year.

Opus Bank acquired Everett, Wash.-based Cascade Financial Corp. and its Cascade Bank in June, a deal that brought 22 offices in the Seattle metropolitan area and boosted its assets to the current level.

Opus Bank expects to complete the acquisition of Fullerton-based RMG Capital Corp. and its savings and loans subsidiary Fullerton Community Bank later this month. That deal is expected to increase the bank's assets to about $3 billion.