SPX sessions closed in negative gamma, with the net-gamma percentile 20 to 50, on CPI days

2 sessions · the archive filtered by the dealer book · all sessions · the calendar

Regime at the close Regime at the open Flip crossings Expected-hold band Direction Size of the move, open to close Net-gamma percentile at the close 0DTE ATM IV at the open Event the day carried Day of the week Year Order

clear filters JSON

2 of 1,101 sessions match. Of them 0% closed above the flip (archive 84%), 50% held the expected-hold band (archive 60%), mean open-to-close move 1.00% (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.

Session	Close	Move	Flip	vs flip	Pctl	Cross	Band	Events
2026-09-11	7,657.42	-0.02%	7,717.1	-59.7	27	2	held	CPI, UMich, Fed
2022-12-13	4,020.22	-1.97%	4,027.2	-7.0	34	14	broke	CPI, Auctions

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.