What is the 13F Pro Quality Score for CSTL?

13F Pro ranks CASTLE BIOSCIENCES INC (CSTL) on the 13F Pro Quality Score, a 0–100 composite of 32 fundamental signals including return on invested capital, free cash flow consistency, balance-sheet strength, earnings quality, growth durability, and valuation discipline. The score refreshes after each 10-K and 10-Q filing on SEC EDGAR. View CSTL's current score at https://13fpro.ai/company/CSTL (free sign-up required for the full ranking).

Which hedge funds own the most CSTL stock?

Based on the most recent Form 13F-HR filings on SEC EDGAR, the largest reported institutional holders of CSTL include BlackRock,, RTW INVESTMENTS,, PRINCIPAL FINANCIAL GROUP. Holdings are reported quarterly within 45 days of quarter-end and updated on https://13fpro.ai/company/CSTL as soon as new 13F filings post.

Where does 13F Pro source CSTL data?

All CASTLE BIOSCIENCES INC fundamentals and ownership data come directly from SEC EDGAR. CASTLE BIOSCIENCES INC files with the SEC under CIK 1447362. 13F Pro ingests XBRL financial facts from 10-K and 10-Q filings, Form 13F-HR institutional holdings, and Form 4 insider transactions, with no third-party rewrites or estimates.

What sector is CSTL in?

CASTLE BIOSCIENCES INC (CSTL) is classified in the Healthcare sector. 13F Pro publishes sector-level fund flow analysis and quality leaders at https://13fpro.ai/research/sector/healthcare.

How often is CSTL research updated on 13F Pro?

CSTL's fundamentals refresh within hours of each new 10-K or 10-Q filing on SEC EDGAR. Institutional ownership updates after each quarterly 13F filing window. Insider transactions update after each Form 4 filing. The 13F Pro Quality Score recalculates after every fundamentals refresh.

CASTLE BIOSCIENCES INC(CSTL)Stock Analysis

AI analysis on 2,800+ stocks →Deep AI analysis on 2,800+ stocks →

Healthcare →Nasdaqsmall

Institutional-grade research for retail investors

SEC EDGAR: CIK 1447362 CSTL stock profile & AI dashboard →

13F Pro Quality Score

40.7/100

Rank #2,093 of 2,962 stocks

View Healthcare peers →

Rankings refresh quarterly once 80% of peers have filed (~45 days after quarter-end). Next update: ~Nov 14, 2026.

Revenue Growth

70.7/100

Profitability

23.4/100

Balance Sheet

25.0/100

Earnings Quality

85.5/100

Free Cash Flow

27.0/100

Institutional Flow

14.7/100

Revenue Scale

32.4/100

Dilution Risk

13.1/100

Email me the moment this company reports earnings

AI Research Report

Two-page plain-English analysis: business, thesis, and three scenarios for the next two years. Refreshed every quarter.

Upgrade to Pro

Pro: 5 reports/month · Pro+: unlimitedOpinion, not investment advice. Do your own research.

Why CSTL Scores 41/100

exact factor attribution · 2026-09-11

CSTL's composite is driven by revenue growth and earnings quality, held back by profitability and free cash flow. Bars show each factor's exact push vs. a median company, using the same weights the ranking engine applies.

Revenue growth

+4.1 pts

71th pct

Earnings quality

+3.5 pts

86th pct

Earnings growth

-0.8 pts

34th pct

Institutional flow

-1.8 pts

15th pct

Shareholder dilution

-1.8 pts

13th pct

Capital efficiency

-2.5 pts

25th pct

Scale

-2.6 pts

32th pct

Free cash flow

-3.5 pts

27th pct

Profitability

-4.0 pts

23th pct

Latest change (2026-08-02): 38 → 32 · ↓ Revenue growth 93→54

Factor percentiles are cross-sectional ranks across the ~2,800-stock scored universe, computed from SEC EDGAR filings. Not investment advice.

CSTL Stock Analysis & AI Quality Score

Data updated 2026-09-11

AI stock analysis and institutional research for CASTLE BIOSCIENCES INC (CSTL), a Healthcare sector company. 13F Pro's AI-powered ranking engine scores CSTL at 40.7/100 on a 32-signal composite quality model, placing it at rank #2,093 of 2,962 stocks — the bottom half of the AI-ranked universe. CSTL scores in the top quartile across earnings quality (85.5). Areas of concern include institutional flow (14.7) and profitability (23.4), which score below median versus the broader universe. Shareholder dilution risk is elevated at 13.1/100, reflecting ongoing share issuance or stock-based compensation. Based on the latest XBRL financial filings (Q2 2026), CASTLE BIOSCIENCES INC reports quarterly revenue of $103.5M, net income of $-2.1M, free cash flow of $6.6M. Top institutional holders of CSTL by reported 13-F value include BlackRock, RTW INVESTMENTS, PRINCIPAL FINANCIAL GROUP, based on the most recent SEC filings. CSTL trades on the Nasdaq exchange and files with the SEC under CIK 1447362. 13F Pro's AI research platform runs 10 specialized AI analysts — value, growth, momentum, macro, and activist specialists — that debate CSTL daily and publish AI-generated analysis with cited SEC sources. The platform aggregates historical XBRL financial facts, 10-Q and 10-K filings, insider Form 4 transactions, and institutional 13-F holdings for CASTLE BIOSCIENCES INC directly from SEC EDGAR. CASTLE BIOSCIENCES INC's 13F Pro composite quality score has ranged between 25 and 55 since 2021, currently 40.7 — a stable long-term trajectory across 68 quarterly and live scoring snapshots.

✦

Fun facts about CASTLE BIOSCIENCES INC

Quirks, history, and lore behind CSTL — the kind of stuff that makes a stock memorable.

1
The Basics
U.S. healthcare company · small-cap · listed on Nasdaq · headquartered in Texas.
2
The Numbers
Annual revenue in the range of roughly $100 million, serving a niche but growing corner of molecular diagnostics — tiny company, outsized clinical ambitions.
3
The History
Founded in the 2010s, it went public around 2019 and built its business around the idea that a single skin biopsy could tell you far more than a pathologist's eye alone.
4
The Secret
Its core products use gene expression profiling to help doctors decide how aggressively to treat melanoma and other skin cancers — sparing some patients from brutal therapies they don't need.
5
The Lore
It has expanded beyond skin cancer into uveal melanoma and Barrett's esophagus testing, turning a dermatology niche into a broader precision oncology platform.
6
The Giveaway
Its flagship test, DecisionDx-Melanoma, is practically synonymous with the company — a biosciences firm named after a fortified structure that's storming the genomic skin-cancer testing market.

▶ Think you know your stocks? Play the Daily Ticker

Revenue

Q2 2026

$103.5M

Net Income

Q2 2026

$-2.1M

Free Cash Flow

Q2 2026

$6.6M

ROIC

Q2 2026

-2.5%

D/E Ratio

Q2 2026

0.03

Period

Revenue & Net Income

Earnings Per Share

Key Financials Over Time

Export Financial Table · Pro

Revenue

+3.7% YoY

$344.2MFY 2025

FY22 $137.0MFY23 $219.8MFY24 $332.1MFY25 $344.2M

Net Income

-232.4% YoY

$-24.2MFY 2025

FY22 $-67.1MFY23 $-57.5MFY24 $18.2MFY25 $-24.2M

Operating Income

-593.8% YoY

$-42.8MFY 2025

FY22 $-72.9MFY23 $-68.0MFY24 $8.7MFY25 $-42.8M

EPS (Diluted)

-233.9% YoY

$-0.83FY 2025

FY22 $-2.58FY23 $-2.14FY24 $0.62FY25 $-0.83

Total Assets

+8.9% YoY

$578.6MFY 2025

FY22 $447.3MFY23 $453.3MFY24 $531.2MFY25 $578.6M

Total Debt

+1.7% YoY

$10.5MFY 2025

FY22 —FY23 $0.00FY24 $10.3MFY25 $10.5M

Op. Cash Flow

-0.8% YoY

$64.3MFY 2025

FY22 $-41.7MFY23 $-5.6MFY24 $64.9MFY25 $64.3M

Free Cash Flow

-22.5% YoY

$28.3MFY 2025

FY22 $-47.3MFY23 $-19.2MFY24 $36.5MFY25 $28.3M

Metric	FY 2025	FY 2024	FY 2023	FY 2022	FY 2021	FY 2020
Revenue	$344.2M +3.7%	$332.1M +51.1%	$219.8M +60.4%	$137.0M +45.7%	$94.1M +50.2%	$62.6M
Net Income	$-24.2M -232.4%	$18.2M +131.7%	$-57.5M +14.4%	$-67.1M -114.6%	$-31.3M -204.3%	$-10.3M
Operating Income	$-42.8M -593.8%	$8.7M +112.8%	$-68.0M +6.7%	$-72.9M -81.8%	$-40.1M -512.6%	$-6.5M
EPS (Diluted)	$-0.83 -233.9%	$0.62 +129.0%	$-2.14 +17.1%	$-2.58 -108.1%	$-1.24 -129.6%	$-0.54
Total Assets	$578.6M +8.9%	$531.2M +17.2%	$453.3M +1.3%	$447.3M -3.3%	$462.6M +5.3%	$439.3M
Total Debt	$10.5M +1.7%	$10.3M	$0.00	—	—	$0.00
Operating Cash Flow	$64.3M -0.8%	$64.9M +1253.0%	$-5.6M +86.5%	$-41.7M -119.4%	$-19.0M -292.4%	$9.9M
Free Cash Flow	$28.3M -22.5%	$36.5M +289.8%	$-19.2M +59.3%	$-47.3M -110.5%	$-22.5M -539.3%	$5.1M

Get alerted when CSTL's score changes

Free account: watchlist tracking, the daily AI brief, and the AI screener.

Passwordless sign-in · Payments by Stripe · Auth by Clerk

Available Research

13F Pro tracks comprehensive data for CASTLE BIOSCIENCES INC including:

SEC EDGAR filings (10-K, 10-Q, 8-K)

XBRL financial facts (revenue, EPS, margins)

Insider transactions (Form 4)

Institutional 13F holdings

Quality rankings (32 signals)

AI analyst debates & daily meetings

Historical financial trends

Peer comparison & sector analysis

Top Institutional Holders of CSTL

BlackRock, Inc.
$78.5M3,291,963 sh
RTW INVESTMENTS, LP
$66.3M2,778,335 sh
PRINCIPAL FINANCIAL GROUP INC
$41.2M1,726,648 sh
VANGUARD CAPITAL MANAGEMENT LLC
$29.3M1,226,497 sh
ACADIAN ASSET MANAGEMENT LLC
$21.9M918,668 sh
VANGUARD PORTFOLIO MANAGEMENT LLC
$20.1M840,785 sh
Allianz Asset Management GmbH
$19.9M811,324 sh
SUMMIT PARTNERS PUBLIC ASSET MANAGEMENT, LLC
$19.7M824,872 sh
STATE STREET CORP
$19.6M822,079 sh
GEODE CAPITAL MANAGEMENT, LLC
$19.0M795,912 sh

Fund	Value	Shares
BlackRock, Inc.	$78.5M	3,291,963
RTW INVESTMENTS, LP	$66.3M	2,778,335
PRINCIPAL FINANCIAL GROUP INC	$41.2M	1,726,648
VANGUARD CAPITAL MANAGEMENT LLC	$29.3M	1,226,497
ACADIAN ASSET MANAGEMENT LLC	$21.9M	918,668
VANGUARD PORTFOLIO MANAGEMENT LLC	$20.1M	840,785
Allianz Asset Management GmbH	$19.9M	811,324
SUMMIT PARTNERS PUBLIC ASSET MANAGEMENT, LLC	$19.7M	824,872
STATE STREET CORP	$19.6M	822,079
GEODE CAPITAL MANAGEMENT, LLC	$19.0M	795,912

Companies Similar to CSTL

Ranked by quality-profile closeness and shared hedge-fund ownership — not just sector membership.

KIDS

ORTHOPEDIATRICS CORP

AI score

Similar quality profile · 5 shared holders

WASATCH ADVISORS LP AIGH Capital Management LLC KENNEDY CAPITAL MANAGEMENT LLC

NVCR

NovoCure Ltd

AI score

Similar quality profile · 8 shared holders

SILVERCREST ASSET MANAGEMENT GROUP LLC Counterpoint Mutual Funds LLC Numerai GP LLC

BDSX

BIODESIX INC

AI score

Similar quality profile · 3 shared holders

AIGH Capital Management LLC PERKINS CAPITAL MANAGEMENT INC Birchview Capital, LP

LUNG

Pulmonx Corp

AI score

Similar quality profile · 4 shared holders

Parkman Healthcare Partners LLC Birchview Capital, LP PERKINS CAPITAL MANAGEMENT INC

VNDA

Vanda Pharmaceuticals Inc.

AI score

Similar quality profile · 5 shared holders

AIGH Capital Management LLC KENNEDY CAPITAL MANAGEMENT LLC China Universal Asset Management Co., Ltd.

XGN

EXAGEN INC.

AI score

Similar quality profile · 4 shared holders

SILVERCREST ASSET MANAGEMENT GROUP LLC KENNEDY CAPITAL MANAGEMENT LLC RTW INVESTMENTS, LP

PTCT

PTC THERAPEUTICS, INC.

AI score

Similar quality profile · 9 shared holders

RTW INVESTMENTS, LP Parkman Healthcare Partners LLC SummitTX Capital, L.P.

ATEC

Alphatec Holdings, Inc.

AI score

Similar quality profile · 9 shared holders

Parkman Healthcare Partners LLC KORNITZER CAPITAL MANAGEMENT INC /KS PERKINS CAPITAL MANAGEMENT INC

Similarity is computed from the 8 composite sub-scores and latest-quarter 13F conviction holdings (index-style filers excluded). Refreshed monthly.

More Healthcare Companies

View all Healthcare →

AAPG

ASCENTAGE PHARMA GROUP INTERNATIONAL

AARD

Aardvark Therapeutics, Inc.

ABBV

AbbVie Inc.

ABCL

AbCellera Biologics Inc.

ABEO

ABEONA THERAPEUTICS INC.

ABOS

Acumen Pharmaceuticals, Inc.

ABPWW

Abpro Holdings, Inc.

ABSI

Absci Corp

Put CSTL on your watchlist

Track score changes the day CASTLE BIOSCIENCES INC files with the SEC, follow the hedge funds that own it, screen 2,800+ AI-scored stocks, and get the daily brief — free.

View Pricing

Free tier includes 13F data, economic indicators, and market overview. Pro starts at $6.67/mo (billed annually).

Passwordless sign-in · Payments by Stripe · Auth by Clerk

Popular Research

AAPL

Apple

MSFT

Microsoft

NVDA

NVIDIA

GOOG

Alphabet

AMZN

Amazon

Is CSTL a good stock to buy?

13F Pro's AI-powered analysis of CASTLE BIOSCIENCES INC (CSTL) draws on SEC EDGAR-sourced fundamentals, institutional 13F holdings, and insider Form 4 transactions in the Healthcare sector (listed on Nasdaq). The 32-signal AI Quality Score, current rank, and full bull/bear verdict for CSTL are available on the CSTL stock profile dashboard — with the same data, AI insights, ratios, and institutional activity refreshed after every 10-K, 10-Q, 13F, and Form 4 filing. CSTL is classified as a small company.

Which hedge funds own CSTL?

Institutional investors are required to disclose their holdings quarterly via SEC Form 13F. 13F Pro aggregates these filings to show which hedge funds, mutual funds, and asset managers are buying or selling CSTL. Combined with insider transaction data from Form 4 filings and AI-powered analysis from 10 specialized research agents, 13F Pro provides a comprehensive view of CASTLE BIOSCIENCES INC's investment landscape.