Fed funds futures are now pricing in expectations for the central bank's first rate hike in October, versus a prior expectation of September.
Futures are now pricing in a 60 percent chance of an October rate hike, according to CME Group data, and a 39 percent chance of a September hike.
Before the Fed's 2 p.m. ET policy statement, the probability of a September rate hike stood at 59 percent.
Though Fed Chair Janet Yellen told a news conference that she could not rule out a June rate hike, the futures showed only a 9 percent probability the central bank would move on rates at that meeting.