The merger of the two brokerage units is expected to be announced sometime after today's closing bell, CNBC's Charlie Gasparino is reporting. Also expected in the next few days is a major overhaul of Citigroup operations that essentially blows up the "financial supermarket" concept. That's when a bank handles a client's every financial need, from investing to insurance. It’s an idea that was heavily pushed by former CEO Sandy Weill (and, with the help of government regulators, allowed for the merger of Citi and Travelers). Citi is apparently receiving big-time pressure from the feds to drastically change the way it does business. Lots of rumors are flying around about what those changes might involve, but massive downsizing would seem to be a given.