While a boost to small institutions, the $80 million in deposits is a fraction of the $8.2 trillion in U.S. bank and thrift deposits insured by the Federal Deposit Insurance Corp.

Four out of five larger credit unions signed up new members during the event, according to the Credit Union National Association's survey of about 1,100 credit unions nationwide. Many respondents said they kept branches open that were typically closed on Saturdays, or extended hours.

A Los Angeles gallery owner launched Bank Transfer Day as a protest against large banks after they began adding new fees. Credit Unions and smaller banks embraced the movement as a way to lure new customers.

Under consumer pressure, Bank of America Corp and other large banks have canceled plans for monthly debit card fees that helped spark the protest.