Bespoke is out with a great chart today showing how markets have performed on Fed day under various Chairmen. Greenspan, Bernanke, Yellen and Powell all sport positive returns -- and Fed day is the single best day to hold stocks, historically -- but the shape of those moves varies wildly.

Fed chair fed day intraday performance
Fed chair fed day intraday performance

Notably, not all these Fed chairs held post-statement press conferences and only Powell held them after every meeting. The current Fed chair has also been at the helm of a far-more-aggressive hiking cycle than the others.

However that's a strong trend of selling in the past 30 minutes of trading, after the press conference ends and given the dump in Europe today along with over-bought conditions in stocks, I think history repeats today.