Castle Biosciences (CSTL) Shares Outstanding (Diluted) (2018 - 2026)
Castle Biosciences' Shares Outstanding (Diluted) was 30.4 million in Q2 2026, up 2.9% from 29.55 million a year earlier and up 1.7% from the prior quarter.
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Analysis
Castle Biosciences (CSTL) Shares Outstanding (Diluted) (2018 - 2026) Analysis & Trends
For FY2025, Shares Outstanding (Diluted) at Castle Biosciences came in at 28.99 million, down 0.9% from FY2024.
- Shares Outstanding (Diluted) shows a five-year compound annual growth rate of 8.9% (FY2020 to FY2025).
- In earlier years, Shares Outstanding (Diluted) was 29.26 million in FY2024 (+9.2%), 26.8 million in FY2023 (+2.9%), 26.05 million in FY2022 (+3.6%) and 25.14 million in FY2021 (+32.8%).
- The Q2 2026 figure marks the highest quarterly Shares Outstanding (Diluted) in data going back to Q3 2018.
- Compared with a year earlier, Shares Outstanding (Diluted) was higher in six of the last eight quarters, with growth averaging 3.9%.
- The best year-over-year quarter for Shares Outstanding (Diluted) over five years was Q4 2021 (growth of 32.8%); the worst was Q3 2025 (a decline of 1.1%).
- Per Business Quant data, CSTL's Shares Outstanding (Diluted) in the three quarters before Q2 2026 was 29.89 million (Q1 2026), 28.99 million (Q4 2025) and 29.07 million (Q3 2025).
Peer Set
Peer Comparison
| # | Company | Market Cap | Enterprise Value | Gross Profit (Qtr) | Shares Outstanding (Dil.) (Qtr) |
|---|---|---|---|---|---|
| 1 | HCA Healthcare | 102.67 Bn | 98.68 Bn | - | 222.83 Mn |
| 2 | Natera | 57.42 Bn | 53.11 Bn | 485.19 Mn | 143.28 Mn |
| 3 | Quest Diagnostics | 27.06 Bn | 25.19 Bn | 1.03 Bn | 112.00 Mn |
| 4 | Labcorp Holdings | 26.94 Bn | 24.68 Bn | 1.11 Bn | 82.00 Mn |
| 5 | Tenet Healthcare | 22.62 Bn | 11.62 Bn | - | 83.96 Mn |
| 6 | Guardant Health | 21.58 Bn | 17.64 Bn | 219.03 Mn | 132.87 Mn |
| 7 | Fresenius Medical Care AG | 12.91 Bn | 4.86 Bn | 1.52 Bn | 612.52 Mn |
| 8 | BrightSpring Health Services | 12.52 Bn | 10.85 Bn | 492.75 Mn | 220.28 Mn |
| 9 | Encompass Health | 12.42 Bn | 12.08 Bn | - | 100.00 Mn |
| 10 | Castle Biosciences | 1.01 Bn | -106.40 Mn | 79.85 Mn | 30.40 Mn |
Historic Data
Download Data
Historic Data
| Date | Value |
|---|---|
| Jun 30, 2026 | 30.40 Mn |
| Mar 31, 2026 | 29.89 Mn |
| Dec 31, 2025 | 28.99 Mn |
| Sep 30, 2025 | 29.07 Mn |
| Jun 30, 2025 | 29.55 Mn |
| Mar 31, 2025 | 28.61 Mn |
| Dec 31, 2024 | 29.26 Mn |
| Sep 30, 2024 | 29.40 Mn |
| Jun 30, 2024 | 28.74 Mn |
| Mar 31, 2024 | 27.49 Mn |
| Dec 31, 2023 | 26.80 Mn |
| Sep 30, 2023 | 26.83 Mn |
| Jun 30, 2023 | 26.73 Mn |
| Mar 31, 2023 | 26.61 Mn |
| Dec 31, 2022 | 26.05 Mn |
| Sep 30, 2022 | 26.32 Mn |
| Jun 30, 2022 | 26.06 Mn |
| Mar 31, 2022 | 25.42 Mn |
| Dec 31, 2021 | 25.14 Mn |
| Sep 30, 2021 | 25.29 Mn |
API Access
Castle Biosciences Shares Outstanding (Diluted) API
Pull this series into your own models, spreadsheets and apps with the Business Quant
Historical Metrics API. The request below matches the chart above — change the
frequency, period or values and it follows. Swap YOUR_API_KEY for your own key.
https://data.businessquant.com/historic?slug=shares-outstanding-diluted&ticker=CSTL&period=max&api_key=YOUR_API_KEYimport requests
url = "https://data.businessquant.com/historic"
params = {"slug": "shares-outstanding-diluted", "ticker": "CSTL", "period": "max", "api_key": "YOUR_API_KEY"}
data = requests.get(url, params=params).json()const res = await fetch("https://data.businessquant.com/historic?slug=shares-outstanding-diluted&ticker=CSTL&period=max&api_key=YOUR_API_KEY");
const data = await res.json();