Fifty percent retracement in the S&P

In 1929, the Dow Jones dropped from 380ish to slightly under 200, a 48% drop. It then rallied to 300 over the next 4 months, which was a 50% move off the bottom. Two years later the Dow Jones stood at 40, down 90% from the high reached in 1929.

In 2008, the S&P 500 future dropped from 1260 to 840, a 33% drop over a 4 week period. It then rallied back 50% to 1050. The Nasdaq 100 future dropped from 1790 to 1200. It then rallied back 50% to 1490. And here we are.