Why the hidden mechanics behind the market’s record run may no longer be helping stocks

The article explains how a surge in S&P 500 call-option buying — especially zero-day-to-expiry (0DTE) calls — helped power April’s record rally by forcing option dealers to buy futures to remain delta neutral, creating a self-reinforcing bid. SpotGamma flagged a record in call buying and cited roughly $13 billion of call-related hedging needs on April 15. The April options expiry (OPEX), in which about 90% of expiring S&P options were calls, cleared many long calls and left dealers with neutral-to-negative hedging needs, which could prompt selling of S&P futures and increase reversal risk. The piece uses MSFT and AAPL option flows as examples and cautions that the same mechanics that boosted the rally can work in reverse, producing heightened volatility.