The parent of First Niagara Bank said Thursday that it has acquired a Norwalk-based insurance brokerage, on the eve of the expected closing of its acquisition of NewAlliance Bank, its first foray into Connecticut.

The purchase of Pierson & Smith, an insurance brokerage, consulting and third-party administration firm, is part of the First Niagara Financial Group’s plans to add to operations, workforce and products and services in the New England Region, the bank said.

The Pierson purchase will add to the Buffalo, N.Y.-based bank’s existing insurance and brokerage services.

Terms of the brokerage transaction, which closed April 8, weren’t disclosed. The NewAlliance acquisition is expected to close Friday.

“This transaction clearly demonstrates First Niagara’s commitment to its newest region and building upon its successful foundation to serve the communities of Connecticut and Massachusetts,” said David Ring, First Niagara’s New England regional president.