With some 401k plans, when you put in a request to move money around, it can take days or weeks. I think this is intentional so that people keep their eye on the big picture instead of "playing the market" with their retirement. My plan used to allow four such moves per year, and it would occur thirty days after the request. That changed a couple of years ago, I'm not sure what the current rules are. But your plan may have a similar structure.