Every StaxInvesting article covering spxw settlement · 2 posts.
2 articles
SPX and SPY both track the S&P 500, and for a 0DTE trader they are not the same instrument. The differences in settlement, exercise style, contract size, and tax treatment are large enough to change your after-tax return and your assignment risk. This is the complete side-by-side, including the two options most comparison pages leave out and an honest account of who SPX is actually wrong for.
Same-day options are now roughly half of all SPX volume, and most people trading them cannot state their settlement terms. This is the full picture: what the contract actually is (European, cash-settled, $100 multiplier, PM settlement), why the last trading day behaves unlike any other day because gamma scales as one over the square root of time remaining, what the research says about who actually makes money, and what execution genuinely requires. The mechanics are knowable. The variance is brutal. Both deserve to be stated plainly.
