How does SPX trade on days 0DTE implied volatility opens at 20% or higher?

SPX sessions with 0DTE IV 20% and above at the open · 118 sessions · the archive filtered by the dealer book · all sessions · the calendar

Short answer. 118 of 1,121 archived SPX sessions matched. Of them 52% closed above the zero-gamma flip (archive 55%) and the mean open-to-close move was 1.23% (archive 0.59%). Counts over finished sessions, recomputed as the archive grows; a share equal to the archive's is a base rate, not a pattern.

118 of 1,121 sessions match. Of them 52% closed above the flip (archive 55%) and the mean open-to-close move was 1.23% (archive 0.59%).

Every row is a finished SPX session and links to its page, where the same numbers stand with the day's events and a free minute-by-minute replay. The filters are the closing measurements those pages print: the zero-gamma flip against the close and the open, the net-gamma percentile, how often the flip was crossed, and the calendar event the day carried. The shares above are counts over the matched days next to the same counts over the whole archive; a share that matches the archive is a base rate, not a pattern.

SessionCloseMoveFlipvs flipPctlCrossEvents
2025-11-216,602.80+0.46%6,611.9-9.16015Fed, Opex
2025-04-305,563.40+1.58%5,500.0+63.4854PCE, GDP, Refunding, VIX settlement, EIA
2025-04-255,525.34+0.71%5,502.6+22.810016Retail sales, UMich
2025-04-245,484.65+1.96%5,455.5+29.2950Housing, Claims, EIA, Auctions
2025-04-235,377.07-0.77%5,390.9-13.8305Housing, VIX settlement, EIA, Auctions, Fed
2025-04-225,287.57+1.51%5,266.2+21.4708Auctions
2025-04-215,159.90-1.34%5,132.5+27.4954
2025-04-175,282.85-0.33%5,299.9-17.04025Housing, Claims, EIA, Fed, Opex
2025-04-165,274.90-1.27%5,286.8-11.94013Retail sales, VIX settlement, EIA, Auctions, Fed
2025-04-145,405.10-0.87%5,418.6-13.42011
2025-04-115,360.72+1.90%5,329.0+31.76510PPI, UMich
2025-04-105,268.22-1.47%5,254.3+13.94523CPI, Claims, EIA, Auctions
2025-04-095,454.52+10.00%5,080.3+374.26014VIX settlement, EIA, Auctions
2025-04-084,987.15-4.77%5,082.6-95.5503Auctions
2025-04-075,063.06+3.30%5,036.6+26.55023Halts
2025-04-045,074.67-3.70%5,158.6-83.9100NFP, Fed
2025-03-315,611.40+1.61%5,564.9+46.5805
2025-03-125,600.19-0.49%5,603.1-2.95021CPI, VIX settlement, EIA, Auctions
2025-03-115,572.65-0.60%5,586.1-13.54025JOLTS, Auctions
2025-03-105,614.39-1.34%5,629.6-15.2402
2025-03-075,769.90+0.73%5,742.0+27.95013NFP, Fed
2025-03-065,737.42-0.50%5,750.9-13.5406Claims, EIA
2025-03-055,841.37+1.00%5,812.8+28.66022Housing, VIX settlement, ISM, EIA, Fed
2025-03-045,778.45-0.48%5,797.6-19.23516
2024-09-185,618.30-0.34%5,636.8-18.53021Housing, VIX settlement, EIA, FOMC
2024-08-085,321.16+1.23%5,301.0+20.1950Claims, EIA, Auctions
2024-08-065,238.87+0.62%5,272.0-33.1358Auctions
2024-08-055,187.74+1.20%5,201.7-14.06521ISM, Fed
2024-08-025,345.79-0.47%5,335.9+9.9805NFP, Housing
2023-03-243,971.87+1.02%3,946.6+25.36518Housing, UMich
2023-03-223,936.62-1.62%3,997.2-60.65024VIX settlement, EIA, FOMC
2023-03-203,950.82+0.61%3,941.8+9.08026
2023-03-173,915.85-0.89%3,919.9-4.12521Opex
2023-03-163,960.81+2.36%3,927.5+33.3905Housing, Claims, EIA
2023-03-153,889.95+0.75%3,868.1+21.87534PPI, Retail sales, VIX settlement, EIA
2023-03-143,920.85+0.32%3,907.2+13.6806CPI
2023-03-133,856.47+0.85%3,874.5-18.14516Halts
2023-03-103,861.60-1.16%3,887.1-25.5256NFP, UMich
2023-02-144,135.67+0.55%4,131.1+4.6456CPI, PPI
2023-02-014,117.72+1.30%4,080.8+36.93521Refunding, VIX settlement, ISM, JOLTS, Housing, EIA, FOMC
2023-01-123,983.75+0.11%3,979.5+4.36012CPI, Claims, EIA, Auctions
2023-01-063,894.32+1.50%3,872.3+22.0855NFP, Housing
2022-12-163,852.14-0.42%3,849.2+2.9427Opex
2022-12-143,997.90-0.60%4,006.1-8.24210VIX settlement, EIA, FOMC
2022-12-134,020.22-1.97%4,027.1-6.91113CPI, Auctions
2022-11-304,075.67+2.89%3,992.4+83.35820GDP, VIX settlement, JOLTS, EIA, Fed, Opex
2022-11-113,993.00+0.80%3,975.8+17.27014UMich
2022-11-103,954.42+1.62%3,911.2+43.3950CPI, Claims, EIA, Auctions
2022-11-093,749.47-1.47%3,780.2-30.8012VIX settlement, EIA, Auctions
2022-11-043,771.49-0.22%3,746.5+25.0804NFP
2022-11-033,721.19+0.09%3,735.6-14.4024Housing, Claims, ISM, EIA
2022-11-023,760.95-2.27%3,829.5-68.62511Refunding, VIX settlement, EIA, FOMC
2022-10-313,871.72-0.10%3,877.0-5.34526Refunding
2022-10-263,830.19+0.09%3,848.3-18.1022Housing, VIX settlement, EIA, Auctions
2022-10-243,798.55+0.85%3,782.0+16.68010
2022-10-213,753.64+2.73%3,713.1+40.68517Opex
2022-10-203,665.52-0.73%3,682.3-16.8155Claims, EIA
2022-10-193,696.65-0.22%3,694.4+2.36010Housing, VIX settlement, EIA, Auctions
2022-10-183,720.90-1.04%3,717.5+3.47022
2022-10-173,678.40+0.56%3,676.0+2.46512
2022-10-143,586.86-2.87%3,615.2-28.3155Retail sales, UMich
2022-10-133,670.01+4.81%3,574.9+95.1751CPI, Claims, EIA, Auctions
2022-10-123,578.17-0.20%3,592.0-13.85032PPI, VIX settlement, Auctions
2022-10-113,587.80-0.17%3,603.9-16.1508
2022-10-103,613.57-1.00%3,619.0-5.55027
2022-10-073,641.52-1.59%3,663.1-21.6453NFP
2022-10-053,780.25+0.84%3,765.4+14.89512VIX settlement, ISM, EIA
2022-10-033,678.02+1.47%3,662.6+15.4706ISM, Housing
2022-09-303,587.67-1.32%3,632.4-44.72015PCE
2022-09-293,640.87-1.14%3,639.9+0.94017GDP, Claims, EIA
2022-09-283,719.20+1.76%3,699.3+19.98512VIX settlement, Fed, EIA, Auctions
2022-09-273,646.87-1.24%3,660.0-13.13510Housing, Confidence, Auctions
2022-09-263,656.12-0.70%3,672.3-16.23014
2022-09-233,693.67-0.62%3,683.7+10.0653UMich
2022-09-223,758.69-0.79%3,767.9-9.24519Claims, EIA
2022-09-213,790.82-2.29%3,857.7-66.93025VIX settlement, EIA, FOMC
2022-09-193,899.47+1.57%3,875.9+23.610021
2022-09-163,874.41+0.45%3,859.4+15.08511Opex
2022-08-264,058.52-3.35%4,116.3-57.806PCE, Fed, UMich
2022-07-274,022.37+1.65%3,995.1+27.3555Housing, VIX settlement, EIA, FOMC
2022-07-143,789.32+0.98%3,763.1+26.2756PPI, Claims, EIA
2022-07-133,803.05+0.84%3,806.4-3.31518CPI, VIX settlement, EIA, Auctions
2022-07-063,844.71+0.30%3,835.7+9.08030VIX settlement, ISM, JOLTS
2022-07-053,831.12+1.66%3,779.5+51.6903Housing
2022-07-013,822.85+0.97%3,789.5+33.38520ISM, Housing
2022-06-303,780.79+0.02%3,780.6+0.2656PCE, Claims, EIA
2022-06-293,818.81-0.17%3,819.7-0.88021GDP, Fed, VIX settlement, EIA
2022-06-233,796.97+0.38%3,772.7+24.3808Claims, Fed, EIA
2022-06-223,760.65+1.10%3,770.5-9.8255Fed, VIX settlement, Auctions
2022-06-213,763.82+0.78%3,758.8+5.1604
2022-06-173,673.32-0.08%3,671.2+2.16023Fed, Opex
2022-06-163,665.62-0.99%3,672.6-7.0551Housing, Claims, EIA
2022-06-153,788.75+0.46%3,784.2+4.55515Retail sales, VIX settlement, EIA, FOMC
2022-06-143,736.39-0.84%3,742.8-6.44013PPI
2022-06-133,751.84-1.38%3,778.8-27.056
2022-06-103,898.87-1.37%3,926.5-27.6012CPI, UMich
2022-06-034,107.97-0.42%4,115.6-7.62520NFP, ISM
2022-05-314,133.06-0.18%4,139.1-6.03019Confidence, Opex
2022-05-264,058.55+1.67%4,052.3+6.3650GDP, Claims, EIA, Auctions, Fed
2022-05-253,978.00+1.23%3,968.7+9.35016Housing, VIX settlement, EIA, Auctions
2022-05-243,940.41+0.19%3,918.4+22.0907Housing, Fed
2022-05-233,973.02+1.01%3,960.4+12.66511
2022-05-203,903.52-0.79%3,864.4+39.1859Opex
2022-05-193,901.97+0.21%3,916.4-14.43533Claims, EIA
2022-05-183,924.20-2.87%3,972.4-48.2262Housing, VIX settlement, EIA, Auctions
2022-05-164,007.44-0.06%4,016.8-9.35320
2022-05-134,023.25+1.24%4,010.7+12.68111Housing, UMich
2022-05-113,934.19-1.40%3,987.5-53.33313CPI, VIX settlement, EIA, Auctions
2022-05-104,001.87-1.59%4,010.9-9.06413
2022-05-093,991.46-1.74%4,030.0-38.6382Fed
2022-05-064,125.09+0.08%4,117.5+7.610022NFP
2022-05-044,300.15+2.88%4,207.1+93.110011Refunding, VIX settlement, ISM, EIA, FOMC
2022-05-034,173.47+0.40%4,174.8-1.37021Housing, JOLTS
2022-05-024,155.12+0.42%4,120.4+34.714ISM, Housing, Refunding
2022-04-294,131.27-2.73%4,202.8-71.54PCE
2022-04-274,185.27-0.12%4,210.7-25.419VIX settlement, EIA, Auctions
2022-04-264,177.05-2.16%4,219.0-41.91Housing, Confidence
2022-04-254,296.66+1.28%4,256.7+40.027Retail sales

Turn a filter into a rule

A count is where a question starts. The Lab takes a rule in plain words ("sell the 0DTE straddle at 10:00 on days that opened below the flip with the percentile under 20"), compiles it against every archived session and reports the out-of-sample verdict with day-clustered intervals. An assistant with the MCP server can page through the same archive with list_sessions and get_session.

Measurements are model output derived from public trade and quote data; they are approximations and can be wrong. Nothing here is investment advice; see the Terms.