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What does 0DTE mean?

0DTE stands for zero days to expiration — options that expire today. On SPX there is an expiration every trading day, so every morning a fresh batch of contracts is born that will be worth exactly their intrinsic value (often zero) by 16:00 ET.

That compression of an option's entire life into one session changes everything:

• Premiums are cheap — little time value remains, so contracts cost a fraction of weekly or monthly options.
• Leverage is extreme — a small index move can multiply a contract's price many times over… or take it to zero.
• Time decay is brutal — theta doesn't tick, it pours. An at-the-money option can lose most of its value over lunch even if the index barely moves.

Why 0DTE options move the market itself

This is the key insight behind the whole platform. When you buy an option, a market maker usually takes the other side. Market makers do not gamble on direction — they hedge by buying or selling the underlying index.

Because 0DTE options carry enormous gamma (their delta changes very fast), market makers must constantly re-hedge as price moves. On days with heavy 0DTE volume, that mechanical hedging flow is large enough to push, pin, or accelerate the index.

In other words: the tail wags the dog. If you can see the hedging pressure, you can anticipate moves that pure price-chart traders never see coming. That is exactly what metrics like GEX, DEX, Vanna and Charm measure.

The intraday rhythm

A 0DTE session is not uniform. Institutional algorithms operate on schedules, and each part of the day has its own character:

• The open — volatility discovery. Overnight positioning unwinds, implied volatility gets crushed, and moves are wide and fast.
• Mid-morning — trend establishment. Institutions position for the day.
• Lunch — the chop zone. Volume dries up, time decay accelerates, and breakouts routinely fail. This window destroys more 0DTE accounts than any other.
• The close — hedging pressure peaks. Expiring options force dealers to aggressively finish their hedges, producing the day's sharpest mechanical moves.

The platform's apps are built around this rhythm — they will explicitly tell you which phase the market is in and how signals should be interpreted in it.

Glossary quick reference

Next: GEX — Gamma Exposure, the most important structural metric of the day.