IBKR Podcasts The Fine Print of Zero DTE Trading
Mar 5, 2026
Matt Cashman, options industry educator with the Option Industry Council and OCC, explains short-dated options mechanics. He compares American vs European exercise rules. He unpacks AutoX and broker contra-exercise windows. He highlights idiosyncratic risks in single-stock zero DTEs and where ETFs and index options fit.
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American Versus European Exercise Mechanics
- American style options can be exercised any time before expiry while European options can only be exercised at the moment of expiry.
- That early-exercise difference creates operational effects after market close that change outcomes for zero DTE trades.
Verify Your Broker's Contra Exercise Cutoff
- Check your broker's specific contra-exercise cutoff and operational rules before trading zero DTE American-style options.
- Brokerage-to-clearing workflows differ and determine whether you can send contra exercise instructions after the market close.
How AutoX Automatically Handles In The Money Options
- AutoX will automatically exercise options meeting a minimal ITM threshold (commonly $0.01) unless the contract is excluded.
- Some option classes are excluded from AutoX (corporate actions, halts), and OCC posts memos for those cases.