Case studies
Case 18Wednesday, July 29, 2026

FOMC in negative gamma: down 77, up 110, down 137

All-expiry gamma was negative every minute. Price travelled 324 points to close 102 lower.

SPX open
7,418.16
High
7,450.84

14:55 ET

Low
7,313.92

15:59 ET

Close
7,316.40
0DTE net gamma positive
22%

of the session's minutes

All-expiry net gamma positive
0%

of the session's minutes

VIX open → close
18.74 → 20.30
VIX high
20.42

The negative gamma regime

The story

  1. All-expiry net gamma negative 100% of minutes; 0DTE negative 78%. VIX 18.7 to 20.5.
  2. Morning: -77 to 7341.25 at 12:15. Then +110 into the statement, high 7450.84, put premium sold -$27M on the way.
  3. Last hour: -137 to 7313.92, through every strike, to the 7325/7320 put spread that had been building since 10:00.
  4. Then what: compare with 06-04. Same kind of event risk is not the variable. The sign of the book is.

Minute by minute

The beats

  1. 10:00 ET

    0DTE -$1.0B, all-expiry -$3.8B

  2. 12:15 ET

    morning low 7341.25 — 77 lower; 7325 building, +$2.8B of puts

  3. 14:55 ET

    session high 7450.84, under 7475 (+$3.1B); puts sold -$27M

  4. 15:58 ET

    7319.65 on the way to the 15:59 low, 7313.92; 7325 at +$17.3B against 7320 at -$22.4B

From the product

The dashboard at each beat

Premium Flow, Cumulative Net Delta and Gamma Flow By Strike on one screen, replayed to the minute. Real frames, nothing redrawn. Click the right of the frame to step to the next beat.

Dashboard frame 1 of 4: 10:00 ET — 0DTE -$1.0B, all-expiry -$3.8B

1 / 4

10:00 ET — 0DTE -$1.0B, all-expiry -$3.8B

More of this session

The short cut

The short cut

7 slides

The case, slide by slide

Slide 1 of 7

1 / 7

These pages describe what the displays show and what the data did on the sessions shown. They are not trading advice, and a past session is not a forecast of a future one.