The U.S. equity market stands at a critical crossroads,SpotGammafounderBrent Kochubasays.

The convergence of the Federal Reserve's interest rate decision and the September expiration of derivatives positions may trigger a scenario similar to last month's turbulence when highly leveraged positions in currencies, stocks, and options unraveled.

"This setup mirrors what we saw on August 1st," Kochuba told SpotGamma subscribers. "Downside volatility may be in excess of what the market is pricing due to the twin triggers of negative gamma and correlation spasms."

Kochuba, known for his analyses and forecasting of markets through the lens of...