The large gap up this morning is quite unusual on the day of a Fed meeting. I ran a test back to 1983 to find other times the market was significantly higher at 1:30pm Eastern time on the day of a Fed meeting. I was only able to find 3 other times where the market was up at least 1.5% by 1:30. On 8/21/84 the market tacked on another 0.04% in the afternoon. On 12/18/84 it added another 1.37%, and on 1/5/88 it lost 0.64%.
It will be interesting to see how today plays out.