Marcus is a bank offering by well-known Goldman Sachs. It is an FDIC insured bank, and pays a higher rate because it has no offices and doesn’t do a lot of advertising. Currently, they are paying 0.50% on a money market savings account, which is higher than most local banks. It’s a pretty good deal — no fees, no hidden costs. So no warnings from me. In fact, I’m glad you brought it to my attention. I might move some money there since every penny counts these days!