# 0DTE Gamma Exposure: What the Front Expiration Measures ## SPX DAILY GEX LEVELS Computed from daily-settled Cboe open interest. Dealer positioning is modeled, not observed. Nothing here is advice. Open interest settlement: 2026-09-24. - **Call wall, settled 2026-09-24. Computed from daily-settled Cboe open interest.** $7,800 - **Put wall, settled 2026-09-24. Computed from daily-settled Cboe open interest.** $7,500 - **Zero-gamma flip, settled 2026-09-24. Computed from daily-settled Cboe open interest.** $7,670 - **Vol trigger, settled 2026-09-24. Computed from daily-settled Cboe open interest.** $7,709 - **Net dealer gamma, settled 2026-09-24. Computed from daily-settled Cboe open interest.** $15.06B - **Largest absolute gamma strike, settled 2026-09-24. Computed from daily-settled Cboe open interest.** $8,000 Source: SquawkFlow URL: https://squawkflow.com/learn/0dte-gamma-exposure Category: Options Greeks Published: 2026-09-21 Updated: 2026-09-22 Type: Explainer > What 0DTE gamma exposure is, what the front expiration's open interest, strike count and net gamma measure, and why walls ranked from it fail late in the session. --- ## The Short Answer 0DTE gamma exposure is dealer gamma computed from the contracts expiring today and nothing else. The measured part is simple: how much open interest the front expiration carries, across how many strikes, and its net dealer gamma. The tempting next step is to rank that one expiration into its own call wall, put wall and zero-gamma flip, separate from the ones a normal GEX page publishes by summing every listed expiration into one profile. That step is harder than it looks, and SquawkFlow withdrew its own front-expiry levels on 2026-09-22 for the reasons this article sets out. The two books describe different things. The all-expiry levels describe where hedging pressure sits across the whole book, including contracts that will still exist in March. The front expiration is the book that stops existing at the close, and it is not a rounding error: on 2026-09-22 it carried about a seventh of the SPX chain's dollar gamma. Whether a level ranked from that book tells you anything is a separate question, and late in the session the answer is that the clock, more than the open interest, decides where such a level lands. If you have not read [what gamma exposure is](/learn/what-is-gamma-exposure-gex) or [how same-day options behave](/learn/zero-dte-options-trading), start with those. This article is only about what changes when you throw every other expiration away. ## Why the Front Expiration Earns Its Own Number An aggregate GEX profile answers one question: across everything listed, where is dealer gamma concentrated? That is genuinely useful and it is also structurally blind to timing. A strike carrying a large figure because of a January contract and a strike carrying the same figure because of a contract expiring in four hours look identical in the sum, and they behave nothing alike. The strike-by-expiration grid, covered in [how to read a gamma exposure heatmap](/learn/gamma-exposure-heatmap), solves half of this by keeping the columns separate so you can see which expiry owns which strike. Front-expiry levels try to solve the other half. Instead of asking you to read a grid and infer where today's flip sits, they compute the flip, the call wall and the put wall from today's column alone. The question they are meant to answer is narrow: does today's book agree with the full book? Asking it with a gamma ranking runs into the problem in the next section, which is that as the session runs the ranking is decided by time to expiry rather than by where the open interest sits. ## What Changes When You Drop Every Other Expiration Three things, and all three are consequences of gamma's relationship with time rather than choices anyone made. **The profile narrows.** Black-Scholes gamma scales roughly as one over the square root of time to expiry, and it is concentrated near the money. As the remaining life of a contract shrinks, the gamma at strikes a few percent away collapses toward nothing while the at-the-money gamma rises. So a front-expiry call wall on the final afternoon is usually a strike close to spot, however much open interest is parked in the wings. The gamma is real: at 3:30pm the wing contracts carry almost no hedging sensitivity left. But it means a wall ranked by gamma on the final afternoon is decided by the clock rather than by where the open interest sits, which is one of the two reasons SquawkFlow withdrew its own front-expiry walls, covered at the end of this article. **The flip moves faster.** The zero-gamma flip is where cumulative dealer gamma changes sign walking up the strike ladder. On the full chain it is anchored by a large, slow-moving book. On today's expiration alone it is anchored by a book that is being consumed by the clock, so it can travel meaningfully within a session while the all-expiry flip barely moves. **Open interest becomes a weaker input.** Open interest is settlement data. It describes positions as of the prior close, so a 0DTE position opened this morning is not in it at all. That limitation applies to every GEX number, but it bites hardest on the front expiration, which is the one accumulating same-day volume. A front-expiry level built on settled open interest is a statement about the book traders carried into today, not about everything they have done since the bell. ## The Time-to-Expiry Problem, and the Floor That Handles It If you compute front-expiry gamma yourself, the first thing that breaks is the clock. Gamma carries time to expiry in a denominator, so as that number approaches zero the computed gamma approaches infinity. Run it naively at 3:59pm and the at-the-money strike returns an enormous figure that is arithmetic rather than positioning. Every implementation handles this by flooring time to expiry at some minimum. The two common choices sit far apart: - **One business day**, often written as 1/262 of a business year. Roughly 33 calendar hours. Simple, and it never divides by anything close to zero. - **A short intraday floor**, for example half an hour expressed in years. SquawkFlow floors at thirty minutes. The reason is that a one-business-day floor prices today's book as though it were tomorrow's, which flattens the same-day gamma peak, and that peak is the entire reason to publish a front-expiry level in the first place. The thirty-minute floor is also the floor this site already applies to charm and vanna for exactly the same divergence, so the front-expiry gamma is bounded on the same clock as its neighbours rather than on a second one. Below half an hour, all three stop being estimates of hedging flow and become artifacts of the division. Whichever floor a tool uses, the honest version states it, because the last hour of a same-day expiration is precisely where the choice changes the printed number. ## When the Two Books Disagree A front-expiry level that matches the all-expiry level tells you the whole chain agrees about that strike. A front-expiry level that sits somewhere else tells you the near book and the far book are built differently, and there are three ordinary reasons why: - **A concentrated same-day position.** A large block in today's expiration can create a wall that simply does not exist anywhere else in the chain. - **A far-dated anchor.** Quarterly and LEAPS open interest at round strikes can hold the all-expiry wall in place long after nothing near-dated supports it. - **Time decay alone.** The front-expiry profile narrows toward spot as the session runs, so the two can drift apart through the day without any new position being opened. None of those is a signal on its own, and none of them says what price will do. The last one is not a small effect either. On SquawkFlow's own data it dominated to the point that the front-expiry walls stopped describing positioning at all, which is why they were withdrawn. A late-session gap between a gamma-ranked front-expiry wall and the all-expiry wall is more likely to be the clock than a position, so it is not a reason to treat the nearer level as the one that matters for the next few hours. ## When There Is No Answer A wall is a ranking over strikes. Rank a thin enough book and the answer is whichever strike happened to be largest, which is noise wearing the costume of a level. So front-expiry levels have to be allowed to refuse. The thresholds SquawkFlow applies before it would publish them are at least 25,000 contracts of open interest on the front expiration and gamma at at least ten distinct strikes. Below either one the levels are served as absent, with the threshold that was not met stated on the page, rather than as a number. A deep index expiration clears both by a wide margin on an ordinary session; a thinly listed name or an unusual expiry may not, and on those the correct output is no level. The levels are currently withdrawn regardless, for the reason below. This matters more than it sounds. Absence served as absence is checkable. A level computed from a book too thin to support it is not, and it looks exactly like a real one. The thresholds are not the only reason a level can be withheld. On 2026-09-22 the SPX front expiration cleared both of them by a wide margin, 350,350 contracts of open interest against the 25,000 floor and more than 200 strikes carrying gamma against the floor of ten, and the levels were withdrawn anyway, for the method reasons in the next section. The page states which reason applies. ## Where These Levels Stand Now The [free SPX GEX page](/gex) carries a front-expiry block beside the all-expiry levels, labelled with the expiration date it was computed from. As of 2026-09-22 the front-expiry flip, call wall and put wall in that block are withdrawn: an audit that day found the flip was being located by rounding noise in the far tail of the ladder and both walls were collapsing onto the strike beside spot, so neither described dealer positioning. The block shows the withdrawal notice in their place. The open interest on that expiration, its strike count and its net gamma are still measured behind it, but they are not printed on the page while the levels are withdrawn. The sections above, on how the two books disagree and on when a level should refuse, describe the construction rather than a number currently on the page. The strike-by-expiration grid behind them is on the [gamma exposure heatmap](/gex-heatmap), and the definitions of the levels themselves are in [call wall and put wall explained](/learn/call-wall-put-wall-explained) and [the GEX flip price](/learn/gex-flip-price-explained). Two limits travel with every number on those pages and are worth restating here. Dealer positioning is an assumption rather than an observation: open interest shows that a contract exists, never which side a dealer holds. And the open interest behind the levels is settled data from the prior close, so nothing in a front-expiry level knows about a position opened this morning. --- ## Citation Source: SquawkFlow, https://squawkflow.com/learn/0dte-gamma-exposure Retrieved: 2026-09-25 08:50 ET Attribution: cite the page URL rather than a copied number. Levels are recomputed every session, so a number without its date is wrong within a day. SquawkFlow publishes market-structure data and education. Nothing here is investment advice, a price target or a recommendation, and we have no order execution.