NIFTY expiry 15 September 2026: what the 23,150 options did in the last 30 minutes
On Tuesday 15 September 2026 the NIFTY strike nearest the index at 15:00 was 23,150. The index went from 23,175 at 15:00 to 23,119 at 15:30, down 56 points across the settle walk.
The at-the-money legs, 15:00 to 15:30
| Leg | 15:00 | High | Low | 15:30 | End vs 15:00 | Open interest |
|---|---|---|---|---|---|---|
| 23,150 CE | ₹66.0 | ₹113 15:20 | ₹0.1 15:30 | ₹0.1 | worthless | 6.1M → 21.7M |
| 23,150 PE | ₹33.6 | ₹55.8 15:21 | ₹9.3 15:20 | ₹31.4 | 0.9× | 17.6M → 11.3M |
Premium of the strike nearest the index at 15:00, sampled every ten seconds from the NSE option chain. Index values are the chain's own quote. Dotted verticals mark a pin-book flip on Gamma Terrain.
What happened
The 23,150 call was ₹66.0 at 15:00. Its high was ₹113 at 15:20. Its low was ₹0.1 at 15:30, less than half of where it started the half hour. It ended at ₹0.1, worthless. Open interest at the strike went from 6.1 million to 21.7 million, so positions were added through the window.
The 23,150 put was ₹33.6 at 15:00. Its high was ₹55.8 at 15:21. Its low was ₹9.3 at 15:20, less than half of where it started the half hour. It ended at ₹31.4, 0.9× the 15:00 price. Open interest at the strike went from 17.6 million to 11.3 million, so positions were closed through the window.
Gamma Terrain's pin-book read flipped: at 15:20 the resting depth read the put strikes below the pin thinning (puts 10 %, calls 233 % of their baseline). A flip names the side whose book is emptying. Across 45 sessions it has not been a direction tell, it is a vacuum tell.
For context, across 21 NIFTY and SENSEX expiries measured to 2026-09-08, 15 of 42 at-the-money legs doubled at some point in this window, 26 lost half, and 13 ended at or above their 15:00 price. This page states what the tape did. It is not a recommendation to buy or sell anything.
Gamma Terrain shows the pin, the walls, the book read and every large print, tick by tick, on NIFTY and SENSEX.
The recap is the after-photo. The terrain is the window while it happens.
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