Goldman Sachs flow of funds guru Scott Rubner absolutely nailed this dramatic and sudden reversal in equity market fortunes:

Feb 12th: "A Bearish Trade Is Developing..." - Goldman Flows Guru Warns Equity Demand Is Slowing

Feb 20th: As $2.7 Trillion OpEx Looms, Goldman Flows Guru Says "I'm On Correction Watch"

So when he speaks, we should listen and after fielding a number of incoming client questions / Global Zoom calls / IB pings over the last week regarding the post-expiry driven equity market sell-off, he is ready to discuss next steps.