Costar Group, Inc. options tape
Read from CBOE's delayed chain on 23 September 2026, with Costar Group, Inc. at $28.80: open interest within 90 days was 11,563 call and 20,234 put contracts, a put/call ratio of 1.75; the day's volume was 243 calls and 361 puts (1.49). The most call open interest sits at the $35.00 strike (3,520 contracts) and the most put open interest at $25.00 (15,883). The at-the-money straddle for 16 October 2026, 23 days out, was priced at 10.7% of spot. For 16 October 2026, implied volatility was 48.1% at the put 5% below spot and 50.0% at the call 5% above, -1.8 points.
Where the open interest sits
| Side | Strike | Open interest |
|---|---|---|
| Calls | $35.00 | 3,520 |
| Puts | $25.00 | 15,883 |
The strike with the most open interest on each side, across expiries within 90 days.
Open interest built since 22 September 2026
| Contract | Open interest now | Change |
|---|---|---|
| 18 December 2026 call at $40.00 | 2,393 | +462 |
Contracts whose open interest rose by 250 or more against the previous day's snapshot.
Source
CBOE delayed quotes for CSGP, the free 15-minute-delayed chain, read once a day. Figures describe positioning; they are not a forecast.
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