What happened to SPX the last time GDP Growth Rate QoQ Adv surprised the market?

The last significant GDP Growth Rate QoQ Advance surprise occurred on July 25 2024. Actual print came in at 2.8% versus consensus of 2.0%. SPX reacted with a sharp 0.9% gap higher at the open and continued climbing another 0.6% intraday, closing up 1.5% on the day.

At that time VIX was already low at 15.8 and dropped another 1.2 points to 14.6 as the positive surprise fueled risk-on sentiment. Iron condor traders who had sold 30-35 delta wings the previous day were immediately tested on both the call side and short put side due to the rapid upward move and compression in implied volatility.

Using the ALVH methodology, the 2.8% print pushed the Actual vs Historical Value reading into the top decile, signaling an elevated probability of continued directional follow-through. Wing-width management became critical. Traders who maintained at least 80-point wide wings on the SPX were able to hold through the initial move while those with tighter 50-point wings were forced to adjust or close at a loss within the first two hours.

This event reinforced the rule that positive GDP surprises in a low VIX environment tend to produce swift upside gaps that challenge the short call side of iron condors more than the put side.