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

SPX sessions with the net-gamma percentile under 20 · 171 sessions · the archive filtered by the dealer book · all sessions · the calendar

Short answer. 171 of 1,103 archived SPX sessions matched. Of them 33% closed above the zero-gamma flip (archive 84%), 16% held the expected-hold band (archive 60%) and the mean open-to-close move was 0.90% (archive 0.60%). Counts over finished sessions, recomputed as the archive grows; a share equal to the archive's is a base rate, not a pattern.

171 of 1,103 sessions match. Of them 33% closed above the flip (archive 84%), 16% held the expected-hold band (archive 60%), mean open-to-close move 0.90% (archive 0.60%).

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, whether the expected-hold band held, 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 flipPctlCrossBandEvents
2026-09-107,591.67-0.03%7,644.0-52.301heldPPI, Claims, EIA, Auctions
2026-09-027,666.27+0.39%7,705.5-39.202brokeHousing, VIX settlement, EIA, Fed
2026-08-177,745.45-0.53%7,745.0+0.402broke
2026-08-057,712.99-0.94%7,720.7-7.707brokeRefunding, VIX settlement, ISM, EIA
2026-07-317,489.97+0.23%7,501.1-11.1025brokeUMich
2026-07-297,317.75-1.35%7,272.6+45.103brokeVIX settlement, EIA, FOMC
2026-07-177,458.16+0.12%7,378.7+79.531heldHousing, UMich, Opex
2026-07-017,483.35+0.14%7,488.2-4.803brokeVIX settlement, ISM, Housing, EIA
2026-06-157,553.95+0.24%7,537.1+16.803broke
2026-06-057,384.59-1.98%7,377.3+7.362brokeNFP
2026-05-297,581.22+0.11%7,584.8-3.621brokeOpex
2026-05-067,365.20+0.85%7,365.2+0.003brokeVIX settlement, EIA
2026-04-227,138.35+0.37%7,078.8+59.6728heldVIX settlement, EIA, Auctions
2026-04-157,023.14+0.66%7,026.0-2.901brokeVIX settlement, EIA, Fed
2026-03-096,795.55+1.63%6,574.3+221.342broke
2025-12-016,812.80+0.09%6,818.7-5.903brokeISM, Fed
2025-11-066,719.47-0.98%6,719.2+0.301brokeEIA
2025-10-276,875.15+0.36%6,785.3+89.801heldAuctions
2025-09-166,607.10-0.26%6,610.2-3.112brokeRetail sales, Auctions
2025-09-156,615.70+0.12%6,522.7+93.050held
2025-09-046,501.80+0.74%6,566.4-64.601brokeClaims, ISM, EIA
2025-07-316,341.46-1.01%6,272.4+69.11512brokePCE, Claims, EIA
2025-05-305,909.25+0.27%5,771.5+137.8160heldPCE, Opex
2025-04-084,987.15-4.77%5,026.0-38.9117brokeAuctions
2025-04-015,632.60+0.78%5,634.1-1.513brokeISM, JOLTS, Housing
2025-03-125,600.19-0.49%5,609.6-9.401brokeCPI, VIX settlement, EIA, Auctions
2025-03-045,778.45-0.48%5,575.4+203.105held
2025-03-035,849.17-2.04%5,819.7+29.504brokeISM, Housing
2025-02-285,952.72+1.50%6,305.7-353.001brokePCE, UMich, Opex
2025-01-246,101.27-0.30%6,101.0+0.301brokeUMich
2024-12-315,883.81-0.71%5,820.0+63.8190heldVIX settlement, Confidence
2024-12-246,037.27+0.92%6,026.6+10.742brokeVIX settlement, Auctions
2024-12-195,867.92-0.91%5,782.3+85.6130heldGDP, Claims, EIA
2024-12-185,872.81-2.88%5,971.1-98.305brokeHousing, VIX settlement, EIA, FOMC
2024-09-115,554.32+1.29%5,616.0-61.702brokeCPI, VIX settlement, EIA, Auctions
2024-08-085,321.16+1.23%5,231.9+89.3131heldClaims, EIA, Auctions
2024-08-055,187.74+1.20%5,080.9+106.8116brokeISM, Fed
2024-07-185,545.79-0.97%5,642.3-96.506brokeClaims, EIA
2024-07-035,534.72+0.42%5,542.0-7.332brokeHousing, Claims, VIX settlement, ISM, EIA
2024-06-125,420.71+0.02%5,421.1-0.4610brokeCPI, VIX settlement, EIA, FOMC
2024-05-315,281.85+0.70%5,180.6+101.300brokePCE, Opex
2024-04-305,036.57-1.21%5,043.8-7.208brokeConfidence
2024-04-155,061.25-1.99%5,067.1-5.904brokeRetail sales
2024-04-095,209.79-0.22%5,137.2+72.613heldAuctions
2024-04-055,204.69+0.84%5,106.0+98.7110heldNFP
2024-03-195,177.35+0.75%5,182.3-4.904brokeHousing, Auctions
2024-03-085,124.37-0.73%5,134.1-9.7018brokeNFP, UMich
2024-02-235,089.57-0.27%5,062.9+26.705heldUMich
2024-02-134,952.15-0.07%4,992.9-40.803brokeCPI
2023-12-224,755.32-0.08%4,728.5+26.802heldPCE, Housing, UMich
2023-12-204,699.15-1.25%4,772.0-72.801brokeVIX settlement, EIA, Auctions
2023-12-154,715.45+0.05%4,673.6+41.801heldOpex
2023-11-294,550.00-0.58%4,541.3+8.701heldGDP, VIX settlement, EIA
2023-11-074,378.87+0.30%4,313.0+65.903brokeAuctions
2023-10-194,278.11-1.04%4,287.6-9.535brokeClaims, EIA
2023-09-294,287.70-0.92%4,264.1+23.6611brokePCE
2023-09-284,298.86+0.73%4,327.6-28.797brokeGDP, Claims, EIA, Auctions
2023-09-214,329.91-1.05%4,337.7-7.8210brokeClaims, EIA
2023-09-154,448.62-0.92%4,454.1-5.508brokeOpex
2023-08-244,376.61-1.71%4,384.5-7.9629brokeHousing, Claims, EIA
2023-08-224,387.54-0.64%4,361.4+26.1121broke
2023-08-214,400.05+0.43%4,405.7-5.601broke
2023-08-174,373.20-1.08%4,371.6+1.667brokeClaims, EIA
2023-08-114,463.11+0.36%4,469.6-6.521brokePPI, UMich
2023-08-104,469.11-0.52%4,472.8-3.787brokeCPI, Claims, EIA, Auctions
2023-08-044,477.02-0.88%4,481.2-4.2011brokeNFP
2023-08-014,576.87+0.05%4,582.7-5.879brokeISM, JOLTS, Housing
2023-07-284,581.45+0.20%4,587.4-5.9192brokePCE, UMich
2023-07-254,567.82+0.33%4,574.0-6.2143brokeConfidence, Auctions
2023-07-244,554.77+0.08%4,559.0-4.201broke
2023-07-104,409.02+0.17%4,370.0+39.001broke
2023-07-064,412.17+0.06%4,412.3-0.1215brokeClaims, ISM, JOLTS, EIA
2023-07-054,446.82+0.22%4,453.0-6.257brokeHousing, VIX settlement, EIA
2023-06-304,450.05+0.51%4,391.7+58.432heldPCE
2023-06-284,377.60+0.24%4,384.8-7.215brokeVIX settlement, EIA, Auctions, Fed
2023-06-124,339.74+0.69%4,339.0+0.723brokeAuctions
2023-06-014,220.32+0.93%4,302.3-82.003brokeClaims, ISM, Housing, EIA
2023-05-304,206.22-0.50%4,170.6+35.673brokeConfidence
2023-05-264,205.21+1.10%4,211.3-6.147brokePCE, Housing, UMich
2023-05-244,115.62-0.28%4,135.1-19.511brokeVIX settlement, EIA, Auctions
2023-05-184,198.80+1.05%4,261.6-62.825brokeClaims, EIA
2023-05-174,158.57+0.71%4,178.7-20.101brokeHousing, VIX settlement, EIA, Auctions
2023-05-024,119.11-0.88%4,126.1-7.0213brokeHousing, JOLTS
2023-04-284,169.52+0.97%4,087.4+82.1164heldPCE, UMich
2023-04-264,057.32-0.58%4,068.7-11.411brokeHousing, VIX settlement, EIA, Auctions
2023-04-254,072.09-1.15%4,072.2-0.11228brokeHousing, Confidence
2023-04-214,133.90+0.10%4,133.8+0.153brokeOpex
2023-04-194,154.52+0.40%4,108.9+45.601heldVIX settlement, EIA, Auctions
2023-04-134,146.20+1.03%4,149.9-3.701brokePPI, Claims, EIA, Auctions
2023-04-104,108.07+0.72%4,015.5+92.610broke
2023-04-064,104.22+0.57%4,105.8-1.627brokeClaims, EIA
2023-03-314,109.76+1.14%4,014.3+95.500brokePCE
2023-03-304,050.82-0.05%4,054.5-3.701brokeGDP, Claims, EIA
2023-03-243,971.87+1.02%3,968.1+3.847brokeHousing, UMich
2023-03-223,936.62-1.62%3,906.4+30.2813brokeVIX settlement, EIA, FOMC
2023-03-153,889.95+0.75%3,883.2+6.8619brokePPI, Retail sales, VIX settlement, EIA
2023-03-143,920.85+0.32%3,921.0-0.223brokeCPI
2023-03-103,861.60-1.16%3,863.4-1.813brokeNFP, UMich
2023-03-093,917.82-2.06%3,950.9-33.101brokeClaims, EIA, Fed, Auctions
2023-03-034,045.96+1.24%4,048.0-2.051brokeISM
2023-02-234,012.80-0.20%4,014.8-2.069brokeGDP, Claims, EIA, Auctions
2023-02-144,135.67+0.55%4,134.4+1.349brokeCPI, PPI
2023-02-094,081.49-1.74%4,089.5-8.029brokeClaims, EIA, Auctions, Fed
2023-02-074,165.82+1.61%4,171.1-5.3011broke
2023-01-203,971.87+1.62%3,869.2+102.700brokeOpex
2023-01-183,927.50-1.98%3,940.2-12.735brokePPI, Retail sales, VIX settlement, Auctions
2023-01-033,824.57-0.83%3,797.0+27.6328brokeISM, Housing
2022-12-303,838.27+0.39%3,840.0-1.715broke
2022-12-273,828.47-0.40%3,829.8-1.337brokeConfidence
2022-12-123,989.64+1.11%3,893.9+95.804brokeAuctions
2022-12-073,934.77+0.00%3,912.1+22.782heldVIX settlement, EIA
2022-12-063,942.12-1.37%3,940.8+1.31814broke
2022-12-024,071.20+0.95%4,079.6-8.405brokeNFP
2022-11-304,075.67+2.89%4,113.2-37.5111brokeGDP, VIX settlement, JOLTS, EIA, Fed, Opex
2022-11-254,027.02+0.04%4,030.5-3.5159brokeUMich, EIA
2022-11-153,991.67-0.71%4,003.5-11.8312brokePPI, Fed
2022-11-143,957.77-0.44%3,969.8-12.0161broke
2022-11-073,807.45+0.48%3,821.1-13.703brokeFed
2022-11-013,857.77-1.35%3,864.2-6.4024brokeISM, JOLTS, Housing
2022-10-273,808.69-0.99%3,818.5-9.8017brokeHousing, GDP, Claims, EIA, Auctions
2022-10-203,665.52-0.73%3,662.8+2.7031brokeClaims, EIA
2022-10-143,586.86-2.87%3,563.8+23.11123brokeRetail sales, UMich
2022-10-133,670.01+4.81%3,674.2-4.2014brokeCPI, Claims, EIA, Auctions
2022-10-103,613.57-1.00%3,619.1-5.5117broke
2022-10-053,780.25+0.84%3,782.9-2.703brokeVIX settlement, ISM, EIA
2022-09-293,640.87-1.14%3,638.4+2.5110brokeGDP, Claims, EIA
2022-09-263,656.12-0.70%3,662.9-6.8411broke
2022-09-233,693.67-0.62%3,672.5+21.21323brokeUMich
2022-09-223,758.69-0.79%3,790.7-32.0523brokeClaims, EIA
2022-09-193,899.47+1.57%3,901.1-1.6018broke
2022-09-163,874.41+0.45%3,890.0-15.6147brokeOpex
2022-09-143,947.10+0.10%3,960.9-13.803brokePPI, VIX settlement, EIA
2022-09-133,931.77-2.27%3,956.7-24.9011brokeCPI, Auctions
2022-09-124,110.17+0.48%4,109.9+0.341heldAuctions
2022-09-094,067.94+0.90%4,075.7-7.873brokeUMich, Fed
2022-09-073,979.57+1.90%3,986.0-6.407brokeVIX settlement
2022-09-023,923.30-1.90%3,955.7-32.416brokeNFP, Housing
2022-08-264,058.52-3.35%4,090.8-32.317brokePCE, Fed, UMich
2022-08-244,140.40+0.32%4,145.2-4.805brokeHousing, VIX settlement, EIA, Auctions
2022-08-234,129.42-0.19%4,132.5-3.187brokeHousing
2022-08-184,283.35+0.17%4,284.7-1.3617brokeClaims, EIA
2022-08-124,279.60+1.21%4,293.4-13.802brokeUMich
2022-08-114,205.50-0.75%4,228.6-23.101brokePPI, Claims, EIA, Auctions
2022-08-094,121.89-0.31%4,125.8-3.902held
2022-08-084,140.82-0.54%4,143.8-3.009broke
2022-08-034,155.25+0.97%4,168.6-13.447heldHousing, Refunding, VIX settlement, ISM, EIA
2022-08-014,120.02+0.36%4,172.5-52.563brokeISM, Housing, Fed, Refunding
2022-07-274,022.37+1.65%4,028.2-5.8513brokeHousing, VIX settlement, EIA, FOMC
2022-07-263,921.47-0.72%3,928.0-6.521heldHousing, Confidence, Auctions
2022-07-253,967.75-0.03%3,982.5-14.8229broke
2022-07-223,962.12-1.02%3,967.1-5.0310brokeUMich
2022-07-203,959.29+0.69%3,966.7-7.4019brokeVIX settlement, EIA, Auctions
2022-07-183,830.77-1.65%3,861.8-31.0010broke
2022-07-143,789.32+0.98%3,798.2-8.9012heldPPI, Claims, EIA
2022-07-083,898.52+0.35%3,905.9-7.4520brokeNFP, UMich
2022-07-073,903.32+0.86%3,904.6-1.3103brokeClaims, EIA
2022-06-283,822.21-2.57%3,851.4-29.211brokeConfidence, Auctions
2022-06-273,898.57-0.70%3,915.1-16.5713brokeHousing, Auctions
2022-06-213,763.82+0.78%3,771.9-8.151held
2022-06-173,673.32-0.08%3,716.2-42.9011brokeFed, Opex
2022-06-163,665.62-0.99%3,727.6-62.091brokeHousing, Claims, EIA
2022-06-133,751.84-1.38%3,779.6-27.813broke
2022-06-103,898.87-1.37%4,034.8-135.903heldCPI, UMich
2022-05-253,978.00+1.23%3,976.3+1.7155brokeHousing, VIX settlement, EIA, Auctions
2022-05-174,088.22+0.45%4,098.2-10.012brokeRetail sales, Fed
2022-05-164,007.44-0.06%3,990.6+16.813broke
2022-05-044,300.15+2.88%4,302.9-2.7124brokeRefunding, VIX settlement, ISM, EIA, FOMC
2022-05-024,155.12+0.42%4,168.1-13.0203brokeISM, Housing, Refunding
2022-04-294,131.27-2.73%4,168.8-37.501brokePCE
2022-04-264,177.05-2.16%4,189.3-12.31413brokeHousing, Confidence
2022-04-184,391.07+0.00%4,435.2-44.1018broke

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.