Treasury investors are used to dealing with an inverted yield curve, but on deposits? At today’s overly liquid banks, the more you deposit, the lower your return may be. It could even be explicitly negative. The retail rates banks offer consumers top wholesale rates, which has some large cash investors buying consumer products. “It’s a remarkable time for the cash industry,” observes Eric Lansky, director of StoneCastle Cash Management, a New York-based registered investment adviser.