Retired auto mechanic Jacob Richard Froess went to cash a check at his long-time branch of AmTrust Bank in Plantation, Fla., when a teller asked him why he was sitting on $100,000 in savings.

Froess told the teller he was waiting for the rates on certificates of deposits to increase. She told him she knew of an investment vehicle that was just as safe but with much higher returns and directed him to a woman sitting at a desk in the bank’s lobby.