This happens frequently on an intraday scale, there's strong evidence that this may have happened with the SPX Horizontal Triangle forming since 1/26/18.
From the 3/23/18 bottom the SPX rallied in three waves and then declined in three waves into the 3/28/18 bottom.
The really interesting part - the SPX bottomed again at the very important 200 day and also touched the Horizontal Triangle rising lower .
The bears had a chance to really push the SPX down a lot on 3/28/18 and failed, stopping at very important support.
There's a high probability the SPX is now in the early part of a rally that will take it to a new all-time high by May 2018.
Thanks for the information.