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Side-by-side financial comparison of CASTLE BIOSCIENCES INC (CSTL) and FOSTER L B CO (FSTR). Click either name above to swap in a different company.

FOSTER L B CO is the larger business by last-quarter revenue ($160.4M vs $87.0M, roughly 1.8× CASTLE BIOSCIENCES INC). On growth, FOSTER L B CO posted the faster year-over-year revenue change (25.1% vs 0.8%). FOSTER L B CO produced more free cash flow last quarter ($19.8M vs $19.7M). Over the past eight quarters, FOSTER L B CO's revenue compounded faster (13.6% CAGR vs 9.2%).

Castle Biosciences Inc. is a commercial-stage diagnostic firm that develops and markets proprietary, clinically actionable tests for dermatological conditions such as melanoma and other skin cancers, plus rare diseases. It operates mainly in the U.S. healthcare market, focusing on segments with high unmet need for more accurate diagnostics to guide treatment choices.

Foster L B Co. is a U.S.-headquartered industrial manufacturing firm that develops, produces and distributes engineered access solutions, construction components, and rail infrastructure products. It serves commercial construction, transportation, and industrial end markets across North America and selected international regions.

CSTL vs FSTR — Head-to-Head

Bigger by revenue
FSTR
FSTR
1.8× larger
FSTR
$160.4M
$87.0M
CSTL
Growing faster (revenue YoY)
FSTR
FSTR
+24.3% gap
FSTR
25.1%
0.8%
CSTL
More free cash flow
FSTR
FSTR
$58.0K more FCF
FSTR
$19.8M
$19.7M
CSTL
Faster 2-yr revenue CAGR
FSTR
FSTR
Annualised
FSTR
13.6%
9.2%
CSTL

Income Statement — Q4 FY2025 vs Q4 FY2025

Metric
CSTL
CSTL
FSTR
FSTR
Revenue
$87.0M
$160.4M
Net Profit
$2.4M
Gross Margin
79.0%
19.7%
Operating Margin
-4.4%
4.9%
Net Margin
1.5%
Revenue YoY
0.8%
25.1%
Net Profit YoY
1098.3%
EPS (diluted)
$-0.06
$0.22

Green = leading value per metric. Periods may differ when fiscal calendars don't align.

8-Quarter Revenue & Profit Trend

Side-by-side quarterly history. Quarters aligned by calendar period so offset fiscal years line up.

Revenue
CSTL
CSTL
FSTR
FSTR
Q4 25
$87.0M
$160.4M
Q3 25
$83.0M
$138.3M
Q2 25
$86.2M
$143.6M
Q1 25
$88.0M
$97.8M
Q4 24
$86.3M
$128.2M
Q3 24
$85.8M
$137.5M
Q2 24
$87.0M
$140.8M
Q1 24
$73.0M
$124.3M
Net Profit
CSTL
CSTL
FSTR
FSTR
Q4 25
$2.4M
Q3 25
$-501.0K
$4.4M
Q2 25
$4.5M
$2.9M
Q1 25
$-25.8M
$-2.1M
Q4 24
$-242.0K
Q3 24
$2.3M
$35.9M
Q2 24
$8.9M
$2.8M
Q1 24
$-2.5M
$4.4M
Gross Margin
CSTL
CSTL
FSTR
FSTR
Q4 25
79.0%
19.7%
Q3 25
77.5%
22.5%
Q2 25
79.5%
21.5%
Q1 25
81.4%
20.6%
Q4 24
81.3%
22.3%
Q3 24
81.8%
23.8%
Q2 24
83.3%
21.7%
Q1 24
81.0%
21.1%
Operating Margin
CSTL
CSTL
FSTR
FSTR
Q4 25
-4.4%
4.9%
Q3 25
-8.2%
6.0%
Q2 25
-4.9%
5.3%
Q1 25
-31.7%
-2.0%
Q4 24
4.7%
2.4%
Q3 24
5.9%
5.3%
Q2 24
5.8%
3.2%
Q1 24
-7.5%
4.5%
Net Margin
CSTL
CSTL
FSTR
FSTR
Q4 25
1.5%
Q3 25
-0.6%
3.1%
Q2 25
5.2%
2.0%
Q1 25
-29.4%
-2.2%
Q4 24
-0.2%
Q3 24
2.6%
26.1%
Q2 24
10.3%
2.0%
Q1 24
-3.5%
3.6%
EPS (diluted)
CSTL
CSTL
FSTR
FSTR
Q4 25
$-0.06
$0.22
Q3 25
$-0.02
$0.40
Q2 25
$0.15
$0.27
Q1 25
$-0.90
$-0.20
Q4 24
$0.32
$-0.04
Q3 24
$0.08
$3.27
Q2 24
$0.31
$0.26
Q1 24
$-0.09
$0.40

Balance Sheet & Financial Strength

Snapshot of each company's liquidity, leverage and book value from the latest quarter.

Metric
CSTL
CSTL
FSTR
FSTR
Cash + ST InvestmentsLiquidity on hand
$299.5M
$4.3M
Total DebtLower is stronger
$10.1M
$42.6M
Stockholders' EquityBook value
$470.9M
$175.3M
Total Assets
$578.6M
$330.4M
Debt / EquityLower = less leverage
0.02×
0.24×

8-quarter trend — quarters aligned by calendar period.

Cash + ST Investments
CSTL
CSTL
FSTR
FSTR
Q4 25
$299.5M
$4.3M
Q3 25
$287.5M
$3.4M
Q2 25
$275.9M
$4.2M
Q1 25
$275.2M
$2.6M
Q4 24
$293.1M
$2.5M
Q3 24
$95.0M
$3.1M
Q2 24
$85.6M
$4.0M
Q1 24
$82.9M
$3.1M
Total Debt
CSTL
CSTL
FSTR
FSTR
Q4 25
$10.1M
$42.6M
Q3 25
$10.0M
$58.6M
Q2 25
$10.0M
$81.4M
Q1 25
$10.0M
$82.3M
Q4 24
$10.0M
$46.8M
Q3 24
$10.0M
$68.4M
Q2 24
$10.0M
$87.0M
Q1 24
$10.0M
$77.9M
Stockholders' Equity
CSTL
CSTL
FSTR
FSTR
Q4 25
$470.9M
$175.3M
Q3 25
$467.0M
$174.8M
Q2 25
$455.4M
$174.4M
Q1 25
$440.3M
$170.8M
Q4 24
$455.8M
$178.3M
Q3 24
$441.1M
$181.9M
Q2 24
$423.9M
$147.1M
Q1 24
$402.5M
$144.6M
Total Assets
CSTL
CSTL
FSTR
FSTR
Q4 25
$578.6M
$330.4M
Q3 25
$562.8M
$333.9M
Q2 25
$544.7M
$349.9M
Q1 25
$501.7M
$342.8M
Q4 24
$531.2M
$334.6M
Q3 24
$514.6M
$344.5M
Q2 24
$487.3M
$333.3M
Q1 24
$458.5M
$326.4M
Debt / Equity
CSTL
CSTL
FSTR
FSTR
Q4 25
0.02×
0.24×
Q3 25
0.02×
0.33×
Q2 25
0.02×
0.47×
Q1 25
0.02×
0.48×
Q4 24
0.02×
0.26×
Q3 24
0.02×
0.38×
Q2 24
0.02×
0.59×
Q1 24
0.02×
0.54×

Cash Flow & Capital Efficiency

How much cash each business actually produces after reinvestment. Cash flow is harder to manipulate than net income.

Metric
CSTL
CSTL
FSTR
FSTR
Operating Cash FlowLast quarter
$26.9M
$22.2M
Free Cash FlowOCF − Capex
$19.7M
$19.8M
FCF MarginFCF / Revenue
22.7%
12.3%
Capex IntensityCapex / Revenue
8.3%
1.5%
Cash ConversionOCF / Net Profit
9.18×
TTM Free Cash FlowTrailing 4 quarters
$28.3M
$25.2M

8-quarter trend — quarters aligned by calendar period.

Operating Cash Flow
CSTL
CSTL
FSTR
FSTR
Q4 25
$26.9M
$22.2M
Q3 25
$22.6M
$29.2M
Q2 25
$20.8M
$10.4M
Q1 25
$-6.0M
$-26.1M
Q4 24
$24.4M
$24.3M
Q3 24
$23.3M
$24.7M
Q2 24
$24.0M
$-5.0M
Q1 24
$-6.8M
$-21.4M
Free Cash Flow
CSTL
CSTL
FSTR
FSTR
Q4 25
$19.7M
$19.8M
Q3 25
$7.8M
$26.4M
Q2 25
$11.6M
$7.7M
Q1 25
$-10.8M
$-28.7M
Q4 24
$16.8M
$22.3M
Q3 24
$17.0M
$21.7M
Q2 24
$18.8M
$-7.0M
Q1 24
$-16.0M
$-24.2M
FCF Margin
CSTL
CSTL
FSTR
FSTR
Q4 25
22.7%
12.3%
Q3 25
9.4%
19.1%
Q2 25
13.4%
5.4%
Q1 25
-12.2%
-29.4%
Q4 24
19.5%
17.4%
Q3 24
19.8%
15.8%
Q2 24
21.6%
-5.0%
Q1 24
-21.9%
-19.4%
Capex Intensity
CSTL
CSTL
FSTR
FSTR
Q4 25
8.3%
1.5%
Q3 25
17.9%
2.0%
Q2 25
10.7%
1.9%
Q1 25
5.4%
2.6%
Q4 24
8.8%
1.5%
Q3 24
7.4%
2.2%
Q2 24
6.0%
1.5%
Q1 24
12.5%
2.2%
Cash Conversion
CSTL
CSTL
FSTR
FSTR
Q4 25
9.18×
Q3 25
6.70×
Q2 25
4.60×
3.61×
Q1 25
Q4 24
Q3 24
10.29×
0.69×
Q2 24
2.69×
-1.74×
Q1 24
-4.83×

Financial Flow Comparison

Revenue → gross profit → operating profit → net profit for each company.

Revenue Breakdown by Segment

CSTL
CSTL

Dermatologic$48.6M56%
Non Dermatologic$38.4M44%

FSTR
FSTR

Rail Technologies And Services Segment$98.0M61%
Over Time Output Method$26.3M16%
Services$19.4M12%
Rail Technologies Products$10.0M6%
Over Time Input Method$8.3M5%

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