Into a big monthly OPEX, huge pinning gamma compresses SPY toward major strikes — ranges tighten, breakouts fail, the tape feels clenched. When all that gamma expires on Friday, the force holding price releases. The days after, frequently starting the following Monday, tend to move more freely. Traders call it the OPEX unclench.

Why the pin releases

The pinning came from dealers hedging concentrated gamma at the big expiring strikes (the mechanism behind pinning). Once those options expire, that gamma — and the mechanical “sell strength, buy weakness” hedging around it — is gone. With the anchor removed, price is freer to trend, and directional flows that were suppressed can finally express.

The clench is expiring gamma pinning price. The unclench is that gamma vanishing at the bell — and price remembering how to move.

Reading the following week

Expect the post-OPEX tape to have a different personality than the pinned run-up: bigger ranges, cleaner trends, breakouts that actually run. It's also when a fresh positioning picture builds for the new cycle, so the flip and walls can relocate meaningfully from where they sat during the clench.

How to use it

Don't carry the pinned-week playbook into the unclench. After a big monthly expiration, be more open to trend and continuation and less quick to fade — the reversion flow that made fades work just expired. Re-read the fresh map early in the new week rather than assuming last week's compressed levels still apply. The unclench is a scheduled regime shift; trade it as one.