This is an educational framework for studying SPY same-day-expiration setups — not a signal service and not advice. Every idea below is defined-risk: you know the most you can lose before you enter.

1. Read the day first

Start with context, not a trade. Check the broad-market direction, the economic calendar, SPY's position relative to VWAP, the opening range, and the prior-day high/low. The regime (trending vs. rangebound) decides which structures even make sense.

2. Match the structure to the regime

• Rangebound / mean-reverting: defined-risk credit spreads or an iron condor placed outside the expected move.
• Trending / expansion: a debit spread in the direction of the trend, entered on a pullback to a level.
• No read: no trade. "Flat" is a position.

3. Place strikes with the expected move

Use the day's expected move (from the at-the-money straddle) to anchor strikes. Selling premium inside the expected move raises risk; placing defined-risk structures around it is the disciplined default.

4. Define the exit before the entry

Write down the profit target, the invalidation level, and the max loss. 0DTE decays fast — a plan you set calmly pre-trade beats one you improvise as theta accelerates.

Risk notes

SPY 0DTE options can lose their entire value the same day, and SPY carries early-assignment risk on in-the-money short legs. Size every trade so a full loss is survivable, and never widen a stop to "give it room."