Sumitomo Bank of California said it had promoted chief operating officer Tomoyuki Kato to succeed president and chief executive officer Tsuneo Onda.
Mr. Onda became chairman of the $4.9 billion-asset unit.
Mr. Kato will manage the integration of the Sumitomo with Zions Bancorp.
The $546 million deal is scheduled to close in the third quarter.
The U.S. unit of Osaka, Japan-based Sumitomo Bank Ltd. went up for sale