Castle Biosciences (CSTL) Options Chain
NASDAQ: CSTLHealth CareMedical SpecialitiesUSD
Market open · Delayed 15 min · as of Oct 8, 4:00 PM ET
Expiration date
- Expiration
- Oct 16, 2026
- Days to expiration
- 7
- Share price
- $33.58
- Put/call ratio (OI)
- 0.13
- Put/call ratio (volume)
- 0.47
- Expected move
- ±$0.2906
- Open interest (C / P)
- 310 / 40
CSTL options summary
The CSTL options chain for the October 16, 2026 expiration lists 10 call and 6 put contracts, with 7 days until expiration. Open interest stands at 310 calls and 40 puts, a put/call ratio of 0.13, which is tilted bullish, with calls outnumbering puts. At-the-money implied volatility near the $35.00 strike is 6.3%, which implies the market expects a move of about ±$0.2906 (0.9%) in Castle Biosciences stock by expiration.
The most open interest sits at the $40.00 call (247 contracts) and the $20.00 put (24 contracts).
Summary generated from market data by MetaCap's automated system. Methodology
CSTL options chain · October 16, 2026
| Calls | Puts | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Last | Bid | Ask | Strike | Bid | Ask | Last | |||||
| 9.30 | 16.60 | 20.50 | 15.00 | 0.00 | 0.95 | 0.20 | |||||
| 4.90 | 6.30 | 10.20 | 17.50 | — | — | — | |||||
| 3.67 | 3.10 | 7.00 | 20.00 | 0.00 | 0.00 | 0.11 | |||||
| 12.62 | 0.00 | 0.00 | 22.50 | — | — | — | |||||
| 8.31 | 0.00 | 0.00 | 25.00 | 0.00 | 0.00 | 0.35 | |||||
| 5.04 | 0.00 | 0.00 | 30.00 | 0.00 | 0.00 | 1.25 | |||||
| 2.75 | 0.00 | 0.00 | 35.00 | 0.00 | 0.00 | 2.00 | |||||
| 0.40 | 0.00 | 0.00 | 40.00 | — | — | — | |||||
| 0.90 | 0.00 | 0.00 | 45.00 | — | — | — | |||||
| 0.70 | 0.00 | 0.00 | 50.00 | 0.00 | 0.00 | 22.35 | |||||
In-the-money callsIn-the-money puts. IV = implied volatility, OI = open interest (contracts). Each contract covers 100 shares. Quotes delayed at least 15 minutes.
Frequently asked questions
What is the CSTL put/call ratio?
For the October 16, 2026 expiration, the CSTL put/call ratio based on open interest is 0.13 (40 puts vs 310 calls), and 0.47 based on today's volume. A ratio above 1 means more puts than calls.
What is CSTL's implied volatility?
At-the-money implied volatility for CSTL options expiring October 16, 2026 is about 6.3%, an annualized estimate of how much the market expects Castle Biosciences stock to move.
How many CSTL option expiration dates are there?
CSTL has 4 listed expiration dates, from Oct 16, 2026 to Apr 16, 2027.
What does "in the money" mean?
A call is in the money when the strike price is below the current share price; a put is in the money when the strike is above it. In-the-money contracts have intrinsic value and are shaded in the table.