Zero Days to Expiration: The Options That Ate the Market
By 2023, options expiring the same day they traded made up 43 percent of all S&P 500 index option volume, up from 5 percent in 2016. The market built a casino that resets every night, and a serious argument about whether it can break the market underneath it.
What 0DTE Means
An option with zero days to expiration, 0DTE, is simply an option on its final day of life. Every option eventually has a 0DTE day. What changed is that traders stopped waiting for it. In 2022 Cboe completed the buildout of S&P 500 index options expiring every single trading day, adding Tuesday and Thursday expirations to the existing Monday, Wednesday and Friday listings. From May 2022 onward, there was always a contract expiring today, and an entire trading culture formed around it.
The appeal is concentration. An option\'s price decays as time passes, a force called theta, and on the last day that decay is a waterfall. A same day S&P 500 option might cost a few dollars per contract in the morning and be worth zero, or fifty times its cost, by 4 p.m. Sellers get to harvest a full option premium in six and a half hours. Buyers get the cheapest possible lottery ticket on the afternoon\'s news. Institutions get a scalpel for hedging a single Fed announcement without paying for time they do not want.
The Numbers
The growth curve was vertical. Zero day contracts went from about 5 percent of S&P 500 index option volume in 2016 to roughly 43 percent by 2023, with total SPX volume itself hitting records at the same time. Estimates of the notional value controlled by a single day\'s 0DTE trading ran to hundreds of billions and, on big days, north of a trillion dollars. By any measure, a market that had not existed in continuous form eighteen months earlier was now the busiest corner of equity derivatives.
| Year | 0DTE share of SPX option volume |
|---|---|
| 2016 | about 5 percent |
| 2021 | growing through the teens and twenties |
| 2023 | about 43 percent |
The Volmageddon Debate
In early 2023, JPMorgan\'s derivatives strategists put a scary number on the phenomenon: in a bad scenario, dealer hedging of 0DTE flows could force tens of billions of dollars of mechanical selling into a falling market, an echo of February 2018, when the implosion of short volatility products cratered the market in an afternoon, an episode traders call Volmageddon. The fear rested on gamma, the rate at which an option\'s directional exposure changes as the market moves. Same day options have enormous gamma, because tiny index moves flip them from worthless to valuable. If dealers as a group end up short that gamma, their hedging buys rallies and sells selloffs, amplifying every move.
Cboe and several banks pushed back with the data they could see: 0DTE flow was remarkably balanced between buyers and sellers, dominated by defined risk spread trades rather than naked positions, leaving dealers\' net exposure small. A trader selling a call spread and a trader buying a put spread largely cancel in the dealer\'s book, and Cboe\'s analysis found the overwhelming majority of the volume structured exactly that way. On this reading, the casino was enormous but self canceling, a giant intraday poker game where the house holds almost no net position.
The whole 0DTE argument compresses to one unobservable number: the market\'s net gamma position. Balanced flow means dealers dampen moves. Lopsided flow means they amplify them. Everyone agrees on the mechanism and nobody can fully see the number.
What It Did to Volatility
One measurable side effect: the VIX, which is built from options with roughly a month to expiration, spent 2023 looking strangely sleepy while intraday action stayed lively. Part of the explanation is that hedging demand migrated from monthly options into same day ones the VIX does not capture. Volatility was not gone, it was being bought and sold intraday and expiring nightly, invisible to the market\'s most famous gauge. Analysts started supplementing the VIX with new one day volatility measures to see it.
Did It Break Anything?
In hindsight, the stress tests came and the cascade did not. The banking scare of March 2023, the August 2024 yen carry unwind, and the tariff convulsions of April 2025 all hit markets carrying record same day option volume, and none of them produced a 0DTE driven doom loop; flows stayed roughly two sided even in panic conditions. That is evidence, not proof, and the honest position is that a lopsided day remains possible. But the burden of the Volmageddon argument got heavier every time the market fell hard for ordinary reasons and the option complex just processed it.
The Bottom Line
0DTE options turned the S&P 500 into a market with a daily heartbeat, where half the option volume is born and dies inside a single session. The growth from 5 percent to 43 percent of volume in seven years is the fastest structural shift in modern derivatives, and it moved real risk from the monthly calendar into the intraday clock. Whether that made markets more fragile or just faster is still argued, but either way, anyone reading the market now has to watch a clock that resets at four.