Webster Financial, parent of Webster Bank, says it has agreed to be acquired for $12.2 billion by global banking giant Banco Santander. Local customers in Danbury and Ridgefield will see no immediate changes, with both companies saying branches will stay open and accounts will operate as usual while the deal moves forward. Santander says the acquisition strengthens its Connecticut footprint and turns it into a top-10 U.S. retail and commercial bank by assets. Webster operates 95 branches statewide, with the transaction expected to close in the second half of this year.