XLF gamma exposure: flip, call wall, put wall

Dealer gamma by strike for Financial Select Sector SPDR, from the option chain itself: two books, the level where net gamma changes sign, and the two strikes that carry the most. Expiries out to 45 days.

data as of 2026-09-18 16:15:00 ET · not updating right now
Spot
55.86
from put-call parity
Zero gamma flip
56.66
1.4% above spot
Call wall
56.00
0.3% above spot
Put wall
54.00
3.3% below spot
Net gamma, volume
-$4M
per 1% move
Net gamma, OI
-$167M
per 1% move
Price sits below the flip at 56.66: on this book dealer hedging adds to a move rather than leaning against it.
Gamma by strike, two books on one axis
OPEN INTEREST · last close
STRIKE
VOLUME · today
60.00
59.50
59.00
58.50
58.00
57.50
57.00
56.50
56.00
call wall · spot
55.50
55.00
54.50
54.00
put wall
53.50
53.00
52.50
52.00
51.50
By expiry, volume book
expiryflipcallputnet
2026-09-2553.2756.0055.00+$4M
2026-09-30n/an/a55.00-$5M
2026-10-02n/a55.0057.00+$117K
2026-10-0956.7957.0053.00-$76K
2026-10-1657.1457.0054.00-$3M
2026-10-2352.7055.5055.00+$52K
How far to trust this bookB

an index or an ETF; the convention holds, the tape is thinner.

Prints a second, regular session0.15
Strikes where the two books agree on the sign78%
Contracts traded today, expiries shown78,512

What this page assumes

  • Calls count as dealer-long gamma and puts as dealer-short. That is a convention, not a measurement: open interest does not say who holds a contract.
  • The volume book signs today's traded contracts. The open-interest book uses positions as of the last close and does not move inside the day.
  • Spot is derived from the option quotes by put-call parity, so it can sit a few cents from the last trade in the underlying.
  • XLF options are American style and the underlying may pay a dividend. Each expiry is priced off its own forward from put-call parity, and gamma is Black-Scholes on that forward. Deep in-the-money contracts near a dividend are the weak spot.
  • Every figure is dollars of dealer delta per 1% move in XLF, the unit that compares across symbols.
  • There is no tape-signed book on this page. That book exists only where a live engine runs.

Questions

What does it mean that XLF is below its flip?

Net dealer gamma on this book is negative, so hedging flows tend to add to a move. It says nothing about direction.

Why are there two books?

Open interest is positioning as it stood at the last close. Volume is what traded today. When they disagree, that split is the reading.

Is this a trading signal?

No. We tested wall touches and flip crosses on SPX across more than a thousand sessions and found no edge that survives costs. These are measurements of where hedging concentrates.

How is this different from the SPX terminal?

SPX runs on a live engine: every second, with a third book signed print by print from the trade tape. This page is rebuilt from chain snapshots and carries the two conventional books only.