# Unusual open interest accumulation

Canonical: https://halfonadouble.com/screens/unusual-open-interest-accumulation
Data through: 2026-09-16 close
Publisher: Half on a Double

Where was the daily increase in open interest at least two standard deviations above its prior-year norm on Sep 16, 2026?

Today's contract change minus the mean of up to 252 preceding daily changes, divided by their sample standard deviation. Today is excluded from the baseline; at least 200 prior changes and 100,000 current contracts are required.

4 published matches, in the same order as the HTML screen.

| Ticker | Close (USD/share) | Open interest (contracts) | 1-day OI change / z-score |
| --- | --- | --- | --- |
| [GFL](https://halfonadouble.com/stock/GFL) | 41.07 | 117,192 | +21,707 · +4.48σ |
| [ARDX](https://halfonadouble.com/stock/ARDX) | 3.39 | 181,069 | +11,772 · +2.27σ |
| [HRL](https://halfonadouble.com/stock/HRL) | 20.79 | 110,722 | +9,366 · +2.12σ |
| [UAL](https://halfonadouble.com/stock/UAL) | 106.30 | 410,615 | +71,575 · +2.10σ |

An em dash means unavailable or not applicable, not zero. [Definitions and limitations](https://halfonadouble.com/methodology.md).