This websites prior blog noted that the S&P 500 (SPX) could break below the 03/11/24 low and bottom in the 5,069 to 5,081 area. Also noted was that an Elliott wave – Horizontal Triangle was an alternate wave count. Today’s opening rally has made the Horizontal Triangle the prime wave count.
The 30 – minute chart courtesy of Trading View shows what happened.

It’s possible the presumed Horizontal Triangle could be complete at the 03/18/24 low.
More likely the SPX could trend down until sometime before the U.S. FOMC announcement due 2:00 PM – EDT on 03/20/24.
After completion of a Horizontal Triangle there’s usually a thrust in the direction of the main trend, which in this case is up.
A move below the SPX bottom at 5,091.41 before a new SPX all-time high will invalidate the Horizontal Triangle wave count.