The entire rally since October 2022 has been based on the rapid depletion of the Fed's reverse repo. When the RR drains rapidly, the money flows directly into the stock market. When the RR gains, it precurses a drop in the stock market.
At each pivot point the stock market has followed suit. We just had the most recent pivot on March 15th through today adding 43% back to the reverse repo. If this increases further, the stock market should move lower.