Usually not much, because the Fed doesn't set mortgage rates in the first place. The Fed sets the federal funds rate, an overnight rate banks charge each other. Mortgage rates are driven by the bond market, tracking the 10-year Treasury and mortgage-backed securities. A widely expected Fed decision is typically priced into bonds before the announcement, so mortgage rates often finish a Fed day close to where they started, even with plenty of intraday noise. And if mortgage rates barely move, there's no new pressure on affordability to shift inventory or prices in the short run. Where a Fed day can matter is a surprise, or the tone of the follow-up commentary. Either one can change what bond investors expect from future policy, and that moves the 10-year Treasury. Whether expectations changed matters more than the headline number itself. For your own purchase, don't hang the decision on a single Fed meeting. The announcement rarely moves your mortgage rate the way people assume, and nobody can promise which way rates head afterward. Buy when it's the right time in your life, on your numbers and your timeline.