SPX (S&P 500 Index)
The Standard & Poor's 500 Index — the benchmark U.S. equity index and the underlying for the world's most liquid options market.
SPX is the ticker symbol for the S&P 500 Index, a market-capitalization-weighted index of the 500 largest U.S. publicly traded companies. It is the most widely followed equity benchmark in the world and the underlying for the largest options market by volume.
Why SPX for 0DTE:
- ●Cash-settled — no assignment risk, no stock delivery
- ●European-style exercise — cannot be exercised early
- ●Section 1256 tax treatment — 60% long-term / 40% short-term capital gains regardless of holding period
- ●Daily expirations — 0DTE options available every trading day (Mon-Fri)
- ●Massive liquidity — tightest bid-ask spreads in the options market
- ●Index-level exposure — diversified, not subject to single-stock risk
SPX vs. SPY for 0DTE:
- ●SPX is 10× the notional value of SPY
- ●SPX options are cash-settled; SPY options can result in share assignment
- ●SPX gets the 60/40 tax advantage; SPY does not
- ●SPX has daily expirations; SPY does as well but with lower liquidity
SPXXL focuses exclusively on SPX because of these structural advantages. The engine's classification system is calibrated specifically for SPX intraday behavior patterns.
Related Terms
Options that expire on the same day they are traded — the fastest-growing segment of the options market with unique risk/reward characteristics.
The aggregate gamma positioning of options market makers — determines how dealer hedging amplifies or dampens SPX price moves.
The CBOE Volatility Index measuring expected 30-day SPX volatility — the market's "fear gauge" and key input to session classification.
A defined-risk options strategy that profits from directional movement — SPXXL's primary recommended structure for most session types.