A Webster Bank branch in downtown Boston. Photo by James Sanna | Banker & Tradesman Staff

A merger of equals between Connecticut-based Webster Bank, which has about 20 branches in Eastern Massachusetts, and New York-based Sterling National Bank will create a bank with about $63 billion in assets and new headquarters in Stamford, Connecticut.

Webster Financial Corp. and Sterling Bancorp announced yesterday that the boards of both companies had unanimously approved an all-stock transaction valued at approximately $10.3 billion, the banks said in a statement. The merger is expected to close in the fourth quarter, subject to regulatory and shareholder approvals and other standard conditions.

The combined bank will keep the Webster Bank name, and Sterling will merge into Webster. Webster shareholders will own approximately 50.4 percent of the combined company, and Sterling shareholders will own about 49.6 percent, on a fully diluted basis, the banks said. Sterling’s shareholders will receive a fixed exchange ratio of 0.463 of Webster stock for each share of Sterling stock.

While the combined bank will establish new corporate headquarters in Stamford, the banks said they would keep a multi-campus presence in the greater New York City area and Waterbury, Connecticut, where Webster is currently based.

“We are bringing together two high-performing organizations with strong cultural and business model alignment to create a powerhouse Northeast bank,” John R. Ciulla, chairman, president & CEO of Webster, said in the statement. “This combination provides exceptional financial benefits and enables us to more aggressively invest in key businesses and activities to enhance value for our customers, our communities, our shareholders and our bankers.”

Ciulla will be president and CEO of the combined company, while Sterling’s current leader, Jack Kopnisky, will be executive chairman for two years. After two years, Ciulla will become chairman, president and CEO, and Kopnisky will continue in a consulting capacity for another 12 months.

The banks said the combined company would provide enhanced potential for revenue, including by expanding selected commercial lending portfolios, growing Webster’s HSA Bank and enhancing the digital banking offerings.

Webster Bank is the second-largest bank headquartered in Connecticut with approximately $32.6 billion in assets. The largest Connecticut-based bank, the $63 billion-asset People’s United Bank, announced in February that it would be acquired by Buffalo-based M&T Bank. After that transaction closes, People’s United branches will become M&T branches, and M&T will keep People’s United’s Bridgeport headquarters as its New England headquarters. People’s United has more than 60 branches across Massachusetts.

Webster is in the process of reducing its branch footprint in New England by about 17 percent, including closing about one-third of the 29 branches it had in Eastern Massachusetts last year. Webster also has branches in Connecticut, Rhode Island and New York.

Sterling is based in Pearl River outside New York City and has about $29.7 billion in assets.

The combined company’s executive management team will have executives from both companies, including Sterling’s Luis Massiani as chief operating officer and Webster’s Glenn MacInnes as chief financial officer. The board of directors will have 15 directors, eight from Webster and seven from Sterling. William Atwell, the current lead independent director of Webster, will be the lead independent director for 24 months after the transaction closes. A legacy Sterling director will then take over as the lead independent director.