How does SPX trade when net dealer gamma sits in its bottom 20th percentile?

SPX sessions with the net-gamma percentile under 20 · 217 sessions · the archive filtered by the dealer book · all sessions · the calendar

Short answer. 217 of 1,136 archived SPX sessions matched. Of them 6% closed above the zero-gamma flip (archive 55%) and the mean open-to-close move was 0.65% (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.

217 of 1,136 sessions match. Of them 6% closed above the flip (archive 55%) and the mean open-to-close move was 0.65% (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
2026-10-207,710.87+0.39%7,715.0-4.11516Housing
2026-10-197,690.22-0.15%7,704.1-13.91529
2026-10-067,819.31+0.08%7,825.7-6.4107Auctions
2026-09-297,669.87-0.27%7,668.6+1.3522Confidence, JOLTS, Auctions
2026-09-237,705.12-0.65%7,716.5-11.302VIX settlement, EIA
2026-09-227,764.70-0.10%7,765.4-0.71023
2026-09-117,657.27-0.02%7,666.6-9.31013CPI, UMich, Fed
2026-09-017,630.64-0.01%7,639.0-8.3108ISM, JOLTS, Housing
2026-08-267,675.54+0.12%7,674.8+0.71018PCE, Housing, GDP, VIX settlement, EIA
2026-08-207,640.30-0.50%7,668.5-28.2029Claims, EIA, Auctions
2026-08-197,706.75-0.22%7,718.9-12.21522VIX settlement, EIA
2026-08-187,690.64-0.22%7,703.7-13.11530Housing, Auctions
2026-08-177,745.45-0.53%7,767.5-22.1010
2026-08-057,712.99-0.94%7,743.6-30.6151Refunding, VIX settlement, ISM, EIA
2026-07-297,317.75-1.35%7,389.8-72.01515VIX settlement, EIA, FOMC
2026-07-227,499.47+0.08%7,507.7-8.2521VIX settlement, EIA
2026-07-207,443.21-0.78%7,469.8-26.61513
2026-07-137,515.25-0.56%7,529.5-14.3021
2026-06-267,339.17+0.36%7,361.2-22.01020UMich, Opex
2026-06-237,365.75+0.13%7,388.9-23.154
2026-06-167,511.70-0.61%7,535.5-23.855Housing
2026-06-087,405.60-0.67%7,431.9-26.3017
2026-06-057,384.59-1.98%7,465.8-81.2152NFP
2026-06-037,554.39-0.60%7,569.5-15.11017Housing, ISM, EIA, Fed
2026-05-277,520.30-0.09%7,517.8+2.51036VIX settlement
2026-05-137,444.67+0.61%7,414.5+30.154PPI, VIX settlement, EIA
2026-05-077,336.90-0.48%7,345.5-8.6155Claims, Housing, EIA
2026-05-047,200.92-0.26%7,205.3-4.454Housing, Fed
2026-05-017,229.45-0.07%7,246.5-17.009ISM
2026-04-217,063.60-0.78%7,091.0-27.4511Retail sales
2026-03-276,369.70-1.16%6,409.8-40.108UMich
2026-03-186,624.85-0.98%6,661.4-36.51010Housing, PPI, VIX settlement, EIA, FOMC
2026-03-136,631.49-1.18%6,654.4-22.9153PCE, Housing, GDP, JOLTS, UMich
2026-03-066,739.82-0.02%6,752.2-12.4518NFP, Retail sales
2026-03-046,870.30+0.40%6,874.3-4.0011ISM, EIA, Fed
2026-01-206,796.40-0.75%6,827.6-31.21611
2026-01-166,939.67-0.33%6,948.7-9.0025Opex
2025-12-316,846.45-0.78%6,876.7-30.257Claims, VIX settlement, EIA
2025-12-306,895.89-0.13%6,902.7-6.81122Confidence
2025-12-186,775.22-0.21%6,786.9-11.61125CPI, Claims, EIA
2025-12-176,722.06-1.21%6,750.0-27.91112VIX settlement, EIA
2025-12-096,840.40-0.07%6,850.4-10.0015JOLTS
2025-12-026,829.84-0.01%6,829.3+0.5515Fed
2025-12-016,812.80+0.09%6,823.4-10.6510ISM, Fed
2025-11-206,539.17-3.04%6,609.1-69.9151NFP, Claims, EIA
2025-11-126,850.86-0.19%6,848.5+2.31033VIX settlement, EIA
2025-11-066,719.47-0.98%6,745.4-25.9012EIA
2025-11-046,771.87-0.17%6,786.8-14.9510
2025-10-306,823.12-0.47%6,854.3-31.21524EIA
2025-10-206,735.32+0.47%6,732.8+2.551
2025-10-106,552.80-2.81%6,626.0-73.1151UMich
2025-10-076,714.25-0.49%6,714.3-0.1159
2025-10-066,740.57+0.06%6,738.5+2.0109
2025-10-036,716.00-0.16%6,728.0-12.055ISM
2025-09-176,600.65-0.18%6,600.3+0.41523Housing, VIX settlement, EIA, FOMC
2025-09-166,607.10-0.26%6,608.4-1.31511Retail sales
2025-09-126,584.85+0.00%6,587.5-2.7523UMich
2025-08-256,439.75-0.23%6,456.1-16.4109Housing
2025-08-156,450.35-0.30%6,455.7-5.4025Retail sales, Opex
2025-08-056,299.50-0.51%6,309.3-9.808ISM
2025-07-316,341.46-1.01%6,385.0-43.5012PCE, Claims, EIA
2025-07-296,371.25-0.54%6,380.0-8.7169Confidence, JOLTS
2025-07-246,363.65-0.07%6,370.7-7.01117Housing, Claims, EIA
2025-07-216,305.80-0.06%6,322.5-16.701
2025-07-156,244.07-0.85%6,261.2-17.2518CPI
2025-06-185,980.50-0.10%5,995.9-15.4017Housing, Claims, VIX settlement, EIA, FOMC
2025-06-096,006.00+0.01%6,010.0-4.0157
2025-06-055,940.05-0.79%5,965.2-25.11511Claims, EIA
2025-06-035,970.55+0.49%5,964.8+5.7151Housing, VIX settlement, JOLTS
2025-05-285,889.85-0.66%5,909.8-20.0523VIX settlement
2025-05-225,841.35+0.03%5,855.2-13.91025Claims, EIA
2025-05-215,845.42-0.99%5,894.9-49.557VIX settlement, EIA
2025-05-065,607.32+0.15%5,618.0-10.71016
2025-05-055,650.12+0.10%5,665.9-15.807ISM
2025-05-015,602.91-0.30%5,626.7-23.8015Claims, ISM, Housing, EIA
2025-04-045,074.67-3.70%5,158.6-83.9100NFP, Fed
2025-03-285,579.60-1.72%5,600.0-20.402PCE, UMich
2025-03-275,692.62-0.05%5,707.0-14.4024GDP, Claims, EIA
2025-02-245,984.55-0.84%6,014.4-29.809
2025-02-216,013.52-1.60%6,059.4-45.806Opex
2025-02-146,114.37-0.07%6,115.6-1.3513Retail sales, UMich
2025-02-076,026.10-1.02%6,039.8-13.7013NFP
2025-01-316,040.37-0.91%6,079.5-39.151PCE
2025-01-175,996.74+0.17%5,998.4-1.6113Housing, Opex
2025-01-165,938.27-0.33%5,946.5-8.21639Retail sales, Claims, EIA
2024-12-136,050.30-0.35%6,051.0-0.7525UMich
2024-12-126,053.17-0.34%6,068.4-15.21621PPI, Claims, EIA, Fed
2024-12-106,034.50-0.37%6,051.2-16.71119
2024-12-096,053.07-0.48%6,064.1-11.11110
2024-12-056,075.36-0.20%6,082.5-7.2029Claims, EIA
2024-11-145,949.37-0.71%5,966.2-16.9011PPI, Claims, EIA
2024-10-315,705.57-1.11%5,730.8-25.256PCE, Claims, EIA
2024-10-305,816.10-0.20%5,832.4-16.3107GDP, Refunding, VIX settlement, EIA
2024-10-285,824.36-0.21%5,832.1-7.8540Refunding
2024-10-255,808.12-0.56%5,825.5-17.31511Housing, UMich
2024-10-175,842.22-0.52%5,851.5-9.31513Retail sales, Claims, EIA
2024-10-155,814.70-0.86%5,834.6-19.905
2024-10-075,694.20-0.66%5,716.1-21.909
2024-09-275,737.72-0.29%5,743.7-6.01011PCE, UMich
2024-09-065,409.24-1.94%5,425.6-16.4155NFP
2024-09-055,500.52-0.36%5,507.3-6.809Claims, ISM, EIA
2024-09-035,527.82-1.55%5,559.4-31.6103ISM, Housing
2024-08-225,571.35-1.23%5,590.9-19.5105Claims, EIA
2024-08-075,200.16-1.89%5,263.6-63.5101VIX settlement, EIA
2024-07-255,399.37-0.56%5,444.3-44.9511Housing, GDP, Claims, EIA
2024-07-245,427.81-1.46%5,461.5-33.6110Housing, VIX settlement, EIA
2024-07-235,555.15-0.16%5,567.1-12.01131
2024-07-155,630.64-0.16%5,638.4-7.71617
2024-07-125,611.87+0.30%5,627.3-15.4161PPI, UMich
2024-07-115,586.17-0.86%5,591.9-5.7115CPI, Claims, EIA
2024-06-285,459.27-0.53%5,486.1-26.805PCE, UMich, Opex
2024-06-245,449.67-0.25%5,465.6-16.007
2024-06-205,472.82-0.43%5,479.7-6.91514Housing, Claims, EIA
2024-06-075,344.87+0.16%5,353.2-8.3517NFP, Fed
2024-05-305,236.40-0.31%5,247.7-11.3529GDP, Claims, EIA
2024-05-295,266.90-0.04%5,273.8-6.9035VIX settlement
2024-05-235,267.81-1.26%5,300.9-33.01516Housing, Claims, EIA
2024-05-225,306.10-0.22%5,307.1-1.0105VIX settlement, EIA
2024-05-205,307.39+0.01%5,313.9-6.503
2024-04-305,036.57-1.21%5,078.3-41.8153Confidence
2024-04-225,009.87+0.34%5,010.4-0.51016
2024-04-194,965.00-0.82%4,981.6-16.6010Opex
2024-04-185,011.00-0.50%5,020.8-9.81011Claims, EIA
2024-04-155,061.25-1.99%5,097.1-35.856Retail sales
2024-03-265,204.49-0.48%5,226.8-22.41022Housing, Confidence
2024-03-135,165.45-0.20%5,169.4-4.01524VIX settlement, EIA
2024-03-085,124.37-0.73%5,146.7-22.451NFP, UMich
2024-03-045,131.65+0.04%5,135.8-4.21525
2024-02-265,069.60-0.46%5,080.8-11.2017Housing
2024-02-204,974.65-0.29%4,971.0+3.71516
2024-02-165,004.90-0.43%5,020.4-15.5019Housing, PPI, Opex
2024-02-125,022.15-0.08%5,030.1-7.91512
2024-02-054,942.95-0.08%4,942.9+0.01511ISM, Fed
2024-01-314,845.54-1.15%4,873.8-28.31526Refunding, VIX settlement, EIA, FOMC
2024-01-244,867.95-0.46%4,886.6-18.6157VIX settlement, EIA
2024-01-224,850.65-0.11%4,852.5-1.91539
2024-01-044,688.65-0.28%4,706.9-18.31014Claims, ISM, EIA
2024-01-034,704.92-0.39%4,716.1-11.2518VIX settlement, JOLTS
2023-12-284,784.19-0.12%4,788.6-4.41533Claims, EIA
2023-12-204,699.15-1.25%4,762.2-63.11120VIX settlement, EIA
2023-12-184,740.65+0.22%4,741.1-0.41615
2023-12-064,549.41-0.88%4,566.4-17.0119VIX settlement, EIA
2023-11-294,550.00-0.58%4,565.3-15.301GDP, VIX settlement, EIA
2023-11-274,551.25-0.13%4,554.1-2.9017Housing
2023-11-094,347.27-0.98%4,368.4-21.1109Claims, EIA
2023-10-264,136.60-0.95%4,153.2-16.61514Housing, GDP, Claims, EIA
2023-10-204,223.91-1.07%4,245.7-21.81017Opex
2023-10-184,313.90-0.94%4,337.2-23.3512Housing, VIX settlement, EIA
2023-09-224,319.57-0.42%4,338.8-19.31014UMich
2023-09-214,329.91-1.05%4,355.3-25.4010Claims, EIA
2023-09-184,454.15+0.13%4,455.3-1.21515
2023-09-154,448.62-0.92%4,461.4-12.704Opex
2023-08-314,509.02-0.29%4,520.5-11.51023PCE, Claims, EIA, Opex
2023-08-304,515.02+0.27%4,512.1+2.91527GDP, VIX settlement, EIA
2023-08-164,404.85-0.68%4,428.8-23.9109Housing, VIX settlement, EIA
2023-08-154,437.62-0.78%4,451.1-13.51513Retail sales
2023-08-104,469.11-0.52%4,484.9-15.8104CPI, Claims, EIA
2023-08-094,467.02-0.71%4,486.6-19.61029VIX settlement, EIA
2023-08-024,513.64-0.70%4,522.8-9.2156Refunding, VIX settlement, EIA
2023-07-274,538.94-1.33%4,575.3-36.41615Housing, GDP, Claims, EIA
2023-07-204,535.79-0.46%4,546.8-11.0117Claims, EIA
2023-07-194,566.39-0.02%4,566.9-0.51633Housing, VIX settlement, EIA
2023-07-144,505.10-0.28%4,511.4-6.31122UMich
2023-07-074,398.87-0.04%4,417.7-18.8117NFP
2023-06-264,329.36-0.37%4,342.1-12.8023
2023-06-234,348.00+0.04%4,353.5-5.41522UMich, Opex
2023-06-164,409.32-0.78%4,425.6-16.3026Opex
2023-06-094,300.50-0.04%4,303.7-3.2523UMich
2023-06-074,267.77-0.50%4,273.2-5.41011VIX settlement, EIA
2023-05-164,110.21-0.37%4,122.4-12.2024Retail sales, Fed
2023-05-094,119.30-0.01%4,123.7-4.4522
2023-05-054,134.90+0.92%4,123.1+11.853NFP
2023-05-044,060.30-0.48%4,064.8-4.5018Claims, EIA
2023-05-014,167.52+0.00%4,173.8-6.359ISM, Housing, Refunding
2023-04-264,057.32-0.58%4,068.1-10.8017Housing, VIX settlement, EIA
2023-04-254,072.09-1.15%4,100.1-28.003Housing, Confidence
2023-04-124,092.20-0.87%4,110.5-18.3108CPI, VIX settlement, EIA
2023-04-114,108.77-0.07%4,113.7-4.91519
2023-03-073,986.70-1.49%4,004.3-17.6158VIX settlement, Fed
2023-03-064,049.27-0.11%4,059.0-9.703Housing
2023-03-013,951.47-0.14%3,955.5-4.0014VIX settlement, ISM, Housing, EIA
2023-02-283,971.07-0.14%3,984.4-13.3012Confidence, Opex
2023-01-274,069.80+0.50%4,071.5-1.759PCE, UMich
2023-01-193,899.05-0.27%3,907.3-8.2513Housing, Claims, EIA
2023-01-183,927.50-1.98%3,959.2-31.7155PPI, Retail sales, VIX settlement
2023-01-173,990.87-0.27%3,994.4-3.5535
2023-01-093,892.52-0.59%3,920.6-28.1153
2022-12-283,783.65-1.19%3,808.3-24.6010VIX settlement
2022-12-193,818.44-0.82%3,822.3-3.8162
2022-12-134,020.22-1.97%4,027.1-6.91113CPI
2022-12-093,933.92-0.49%3,958.7-24.8015PPI, UMich, Fed
2022-11-283,966.47-0.87%3,986.9-20.459
2022-11-254,027.02+0.04%4,028.3-1.31025UMich, EIA
2022-11-093,749.47-1.47%3,780.2-30.8012VIX settlement, EIA
2022-11-033,721.19+0.09%3,735.6-14.4024Housing, Claims, ISM, EIA
2022-10-273,808.69-0.99%3,827.2-18.5011Housing, GDP, Claims, EIA
2022-10-263,830.19+0.09%3,848.3-18.1022Housing, VIX settlement, EIA
2022-10-203,665.52-0.73%3,682.3-16.8155Claims, EIA
2022-10-143,586.86-2.87%3,615.2-28.3155Retail sales, UMich
2022-09-153,902.26-0.71%3,923.0-20.8010Retail sales, Claims, EIA

Showing the first 200 of 217; the JSON carries all of them.

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.