CSTL
Castle Biosciences, Inc.
Medical - Diagnostics & Research
Market Cap$583M
5Y Perf.-49.9%
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Stock Comparison
CSTL vs FLGT
Revenue, margins, valuation, and 5-year total return — side by side.
FLGT
Fulgent Genetics, Inc.
Medical - Diagnostics & Research
Market Cap$449M
5Y Perf.-13.3%
CSTL vs FLGT — Key Financials
Market cap, revenue, margins, and valuation side-by-side.
| Company Snapshot | CSTL | FLGT |
|---|---|---|
| Industry | Medical - Diagnostics & Research | Medical - Diagnostics & Research |
| Market Cap | $583M | $449M |
| Revenue (TTM) | $340M | $323M |
| Net Income (TTM) | $-13M | $-61M |
| Gross Margin | 48.5% | 40.6% |
| Operating Margin | -8.6% | -28.2% |
| Total Debt | $37M | $476K |
| Cash & Equiv. | $117M | $50M |
CSTL vs FLGT — Long-Term Stock Performance
Price return indexed to 100 at period start. Dividends excluded.
CSTL
FLGT
| Stock | May 20 | May 26 | Return |
|---|---|---|---|
| Castle Biosciences,… (CSTL) | 100 | 50.1 | -49.9% |
| Fulgent Genetics, I… (FLGT) | 100 | 86.7 | -13.3% |
Price return only. Dividends and distributions are not included.
Quick Verdict: CSTL vs FLGT
Each card shows where this stock fits in a portfolio — not just who wins on paper.
Bottom line: CSTL leads in 4 of 6 categories, making it the strongest pick for profitability and margin quality and capital preservation and lower volatility. Fulgent Genetics, Inc. is the stronger pick specifically for growth and revenue expansion. As sector peers, any of these can serve as alternatives in the same allocation.
CSTL
Castle Biosciences, Inc.
The Income Pick
CSTL carries the broadest edge in this set and is the clearest fit for income & stability and sleep-well-at-night.
- beta 0.88
- Lower volatility, beta 0.88, Low D/E 7.8%, current ratio 5.26x
- Beta 0.88, current ratio 5.26x
Best for: income & stability and sleep-well-at-night
FLGT
Fulgent Genetics, Inc.
The Growth Play
FLGT is the clearest fit if your priority is growth exposure and long-term compounding.
- Rev growth 13.8%, EPS growth -39.7%, 3Y rev CAGR -19.5%
- 64.6% 10Y total return vs CSTL's -10.1%
- 13.8% revenue growth vs CSTL's 3.7%
Best for: growth exposure and long-term compounding
See the full category breakdown
| Category | Winner | Why |
|---|---|---|
| Growth | FLGT | 13.8% revenue growth vs CSTL's 3.7% |
| Quality / Margins | CSTL | -3.8% margin vs FLGT's -18.8% |
| Stability / Safety | CSTL | Beta 0.88 vs FLGT's 0.97 |
| Dividends | Tie | Neither stock pays a meaningful dividend |
| Momentum (1Y) | CSTL | +12.8% vs FLGT's -19.0% |
| Efficiency (ROA) | CSTL | -2.3% ROA vs FLGT's -5.0%, ROIC -8.5% vs -6.4% |
CSTL vs FLGT — Revenue Breakdown by Segment
How each company's revenue is distributed across its business units
FY 2025
FY 2025
CSTL vs FLGT — Financial Metrics
Side-by-side numbers across 2 stocks — who leads on profitability, valuation, growth, and risk.
BEST OVERALLCSTLLAGGINGFLGT
FLGTFulgent Genetics, Inc.
2leads
CSTLCastle Biosciences, I…
2leads
6 Total Categories
CATEGORYLEADERvs FLGTMETRICS WON
Income & Cash FlowRevenue, margins, and cash flow strength
CSTL5/6
Valuation MetricsMultiples, price ratios, and targets
FLGT2/3
Profitability & EfficiencyROE, ROIC, leverage, and quality scores
FLGT5/9
Total Returns1Y, 3Y, 5Y total returns with dividends
CSTL4/6
Risk & VolatilityBeta, volatility, and downside exposure
Tied
—
Analyst OutlookRatings, price targets, and dividends
—
—
Income & Cash Flow (Last 12 Months)
CSTL leads this category, winning 5 of 6 comparable metrics.
Income & Cash Flow (Last 12 Months)
CSTL and FLGT operate at a comparable scale, with $340M and $323M in trailing revenue. CSTL is the more profitable business, keeping -3.8% of every revenue dollar as net income compared to FLGT's -18.8%. On growth, FLGT holds the edge at +9.3% YoY revenue growth, suggesting stronger near-term business momentum.
| Metric | CSTLCastle Bioscience… | FLGTFulgent Genetics,… |
|---|---|---|
| RevenueTrailing 12 months | $340M | $323M |
| EBITDAEarnings before interest/tax | -$16M | -$67M |
| Net IncomeAfter-tax profit | -$13M | -$61M |
| Free Cash FlowCash after capex | $5M | -$124M |
| Gross MarginGross profit ÷ Revenue | +48.5% | +40.6% |
| Operating MarginEBIT ÷ Revenue | -8.6% | -28.2% |
| Net MarginNet income ÷ Revenue | -3.8% | -18.8% |
| FCF MarginFCF ÷ Revenue | +1.3% | -38.5% |
| Rev. Growth (YoY)Latest quarter vs prior year | -4.9% | +9.3% |
| EPS Growth (YoY)Latest quarter vs prior year | +45.6% | -3.0% |
CSTL leads this category, winning 5 of 6 comparable metrics.
Valuation Metrics
FLGT leads this category, winning 2 of 3 comparable metrics.
Valuation Metrics
| Metric | CSTLCastle Bioscience… | FLGTFulgent Genetics,… |
|---|---|---|
| Market CapShares × price | $583M | $449M |
| Enterprise ValueMkt cap + debt − cash | $503M | $400M |
| Trailing P/EPrice ÷ TTM EPS | -23.18x | -7.67x |
| Forward P/EPrice ÷ next-FY EPS est. | — | — |
| PEG RatioP/E ÷ EPS growth rate | — | — |
| EV / EBITDAEnterprise value multiple | — | — |
| Price / SalesMarket cap ÷ Revenue | 1.69x | 1.39x |
| Price / BookPrice ÷ Book value/share | 1.18x | 0.42x |
| Price / FCFMarket cap ÷ FCF | 20.58x | — |
FLGT leads this category, winning 2 of 3 comparable metrics.
Profitability & Efficiency
FLGT leads this category, winning 5 of 9 comparable metrics.
Profitability & Efficiency
CSTL delivers a -2.8% return on equity — every $100 of shareholder capital generates $-3 in annual profit, vs $-5 for FLGT. FLGT carries lower financial leverage with a 0.00x debt-to-equity ratio, signaling a more conservative balance sheet compared to CSTL's 0.08x. On the Piotroski fundamental quality scale (0–9), FLGT scores 4/9 vs CSTL's 3/9, reflecting mixed financial health.
| Metric | CSTLCastle Bioscience… | FLGTFulgent Genetics,… |
|---|---|---|
| ROE (TTM)Return on equity | -2.8% | -5.4% |
| ROA (TTM)Return on assets | -2.3% | -5.0% |
| ROICReturn on invested capital | -8.5% | -6.4% |
| ROCEReturn on capital employed | -8.6% | -8.0% |
| Piotroski ScoreFundamental quality 0–9 | 3 | 4 |
| Debt / EquityFinancial leverage | 0.08x | 0.00x |
| Net DebtTotal debt minus cash | -$80M | -$50M |
| Cash & Equiv.Liquid assets | $117M | $50M |
| Total DebtShort + long-term debt | $37M | $476,000 |
| Interest CoverageEBIT ÷ Interest expense | -270.94x | -354.75x |
FLGT leads this category, winning 5 of 9 comparable metrics.
Total Returns (Dividends Reinvested)
CSTL leads this category, winning 4 of 6 comparable metrics.
Total Returns (Dividends Reinvested)
A $10,000 investment in CSTL five years ago would be worth $3,190 today (with dividends reinvested), compared to $2,024 for FLGT. Over the past 12 months, CSTL leads with a +12.8% total return vs FLGT's -19.0%. The 3-year compound annual growth rate (CAGR) favors CSTL at -5.3% vs FLGT's -23.0% — a key indicator of consistent wealth creation.
| Metric | CSTLCastle Bioscience… | FLGTFulgent Genetics,… |
|---|---|---|
| YTD ReturnYear-to-date | -50.1% | -41.0% |
| 1-Year ReturnPast 12 months | +12.8% | -19.0% |
| 3-Year ReturnCumulative with dividends | -15.0% | -54.4% |
| 5-Year ReturnCumulative with dividends | -68.1% | -79.8% |
| 10-Year ReturnCumulative with dividends | -10.1% | +64.6% |
| CAGR (3Y)Annualised 3-year return | -5.3% | -23.0% |
CSTL leads this category, winning 4 of 6 comparable metrics.
Risk & Volatility
Evenly matched — CSTL and FLGT each lead in 1 of 2 comparable metrics.
Risk & Volatility
CSTL is the less volatile stock with a 0.88 beta — it tends to amplify market swings less than FLGT's 0.97 beta. A beta below 1.0 means the stock typically moves less than the S&P 500. FLGT currently trades 48.7% from its 52-week high vs CSTL's 43.5% drawdown — a narrower gap to the peak suggests stronger recent price momentum.
| Metric | CSTLCastle Bioscience… | FLGTFulgent Genetics,… |
|---|---|---|
| Beta (5Y)Sensitivity to S&P 500 | 0.88x | 0.97x |
| 52-Week HighHighest price in past year | $44.28 | $31.04 |
| 52-Week LowLowest price in past year | $14.59 | $13.46 |
| % of 52W HighCurrent price vs 52-week peak | +43.5% | +48.7% |
| RSI (14)Momentum oscillator 0–100 | 48.1 | 43.0 |
| Avg Volume (50D)Average daily shares traded | 363K | 697K |
Evenly matched — CSTL and FLGT each lead in 1 of 2 comparable metrics.
Analyst Outlook
Insufficient data to determine a leader in this category.
Analyst Outlook
Wall Street rates CSTL as "Buy" and FLGT as "Buy". Consensus price targets imply 148.4% upside for CSTL (target: $48) vs 138.3% for FLGT (target: $36).
| Metric | CSTLCastle Bioscience… | FLGTFulgent Genetics,… |
|---|---|---|
| Analyst RatingConsensus buy/hold/sell | Buy | Buy |
| Price TargetConsensus 12-month target | $47.80 | $36.00 |
| # AnalystsCovering analysts | 11 | 9 |
| Dividend YieldAnnual dividend ÷ price | — | — |
| Dividend StreakConsecutive years of raises | — | 1 |
| Dividend / ShareAnnual DPS | — | — |
| Buyback YieldShare repurchases ÷ mkt cap | 0.0% | +2.4% |
Insufficient data to determine a leader in this category.
Key Takeaway
CSTL leads in 2 of 6 categories (Income & Cash Flow, Total Returns). FLGT leads in 2 (Valuation Metrics, Profitability & Efficiency). 1 tied.
Best OverallCastle Biosciences, Inc. (CSTL)Leads 2 of 6 categories
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CSTL vs FLGT: Frequently Asked Questions
8 questions · data-driven answers · updated daily
01Is CSTL or FLGT a better buy right now?
For growth investors, Fulgent Genetics, Inc.
(FLGT) is the stronger pick with 13. 8% revenue growth year-over-year, versus 3. 7% for Castle Biosciences, Inc. (CSTL). Analysts rate Castle Biosciences, Inc. (CSTL) a "Buy" — based on 11 analyst ratings — the highest consensus in this comparison. The "better buy" depends entirely on your goals: growth investors should weight revenue trajectory, value investors should weight P/E and PEG, and income investors should weight dividend yield and streak.
02Which is the better long-term investment — CSTL or FLGT?
Over the past 5 years, Castle Biosciences, Inc.
(CSTL) delivered a total return of -68. 1%, compared to -79. 8% for Fulgent Genetics, Inc. (FLGT). Over 10 years, the gap is even starker: FLGT returned +64. 6% versus CSTL's -10. 1%. Past returns do not guarantee future results, and the stock with the higher historical return may already have its best growth priced in.
03Which is safer — CSTL or FLGT?
By beta (market sensitivity over 5 years), Castle Biosciences, Inc.
(CSTL) is the lower-risk stock at 0. 88β versus Fulgent Genetics, Inc. 's 0. 97β — meaning FLGT is approximately 10% more volatile than CSTL relative to the S&P 500. On balance sheet safety, Fulgent Genetics, Inc. (FLGT) carries a lower debt/equity ratio of 0% versus 8% for Castle Biosciences, Inc. — giving it more financial flexibility in a downturn.
04Which is growing faster — CSTL or FLGT?
By revenue growth (latest reported year), Fulgent Genetics, Inc.
(FLGT) is pulling ahead at 13. 8% versus 3. 7% for Castle Biosciences, Inc. (CSTL). On earnings-per-share growth, the picture is similar: Fulgent Genetics, Inc. grew EPS -39. 7% year-over-year, compared to -233. 9% for Castle Biosciences, Inc.. Over a 3-year CAGR, CSTL leads at 35. 9% annualised revenue growth. Higher growth typically commands a higher valuation multiple — check whether the premium P/E or P/S is justified by the growth rate using the PEG ratio.
05Which has better profit margins — CSTL or FLGT?
Castle Biosciences, Inc.
(CSTL) is the more profitable company, earning -7. 0% net margin versus -18. 8% for Fulgent Genetics, Inc. — meaning it keeps -7. 0% of every revenue dollar as bottom-line profit. Operating margin tells a similar story: CSTL leads at -12. 4% versus -28. 2% for FLGT. At the gross margin level — before operating expenses — CSTL leads at 68. 7%, reflecting greater pricing power or product mix advantage. Stronger margins indicate durable pricing power, lower cost of revenue, or higher mix of software/services. They are one of the clearest signs of business quality.
06Which pays a better dividend — CSTL or FLGT?
None of the stocks in this comparison currently pay a material dividend.
All are effectively zero-yield and should be held for capital appreciation rather than income.
07Is CSTL or FLGT better for a retirement portfolio?
For long-horizon retirement investors, Castle Biosciences, Inc.
(CSTL) is the stronger choice — it scores higher on the combination of lower volatility, dividend reliability, and long-term compounding (low volatility (β 0. 88)). Both have compounded well over 10 years (CSTL: -10. 1%, FLGT: +64. 6%), confirming both are viable long-term holds — but the lower-volatility option typically results in less emotional selling during corrections. Retirement portfolios generally favour predictability over maximum returns. Consult a financial advisor before making allocation decisions.
08What are the main differences between CSTL and FLGT?
Both stocks operate in the Healthcare sector, making this a peer-level intra-sector comparison — the same macro tailwinds and headwinds will affect both.
These fundamental differences mean investors should not choose between them on a single metric — the "better stock" depends entirely on which of these characteristics aligns with your investment strategy.
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