Top 15 Diagnostics & Research Medical Stocks
Marvin ranks 15 diagnostics and research stocks by Overall score within their industry. Quest Diagnostics, Medpace and Veracyte lead, while Illumina is last on this list.
Diagnostics and research companies help doctors, labs and scientists test, measure and study health and disease. Some run testing labs, some make lab instruments, and some support research work for other firms. This list covers 15 companies from that industry, ordered by Marvin's Overall score.
The mix is wide. Some companies on the list are solidly profitable with steady growth, while others are growing fast but still losing money. The blurbs below point out each company's strengths and weak spots using figures from its latest fiscal year.
Marvin's scores only describe how each company compares with others in its industry today. A high score is not a prediction, and a lower-ranked company can still be a strong business. Use the list as a starting point for your own research.
The list
How Marvin ranked these stocks
Marvin included companies above a minimum size cutoff in the Medical - Diagnostics & Research industry and ranked them by Overall score, highest first. Scores run on a scale from zero to one hundred and are relative to each company's own industry, so a score compares a company with its industry peers, not with every stock in the market. The data is as of October 2026.
Companies above about $300 million in size, ranked by Marvin scores (0-100, relative to each company's own industry). The Medical - Diagnostics & Research industry, highest Overall score first.
The stocks, one by one
Quest Diagnostics Incorporated DGX
Quest Diagnostics has the top Overall score of 95, with a quality score of 88. Revenue grew 11.8% last fiscal year and operating margin was 14.1%. Caution: debt-to-equity of 0.85 means some borrowing, and the margin is moderate rather than high.
Medpace Holdings, Inc. MEDP
Medpace Holdings posted growth of 20.0%, an operating margin of 21.0% and a free cash flow margin of 25.4%, which points to a strongly profitable business. Return on equity is 113.3%. Caution: debt and gross margin data are unavailable, so leverage can't be judged.
Veracyte, Inc. VCYT
Veracyte combines a gross margin of 71.7% with a free cash flow margin of 29.5% and revenue growth of 16.0%, a healthy mix of growth and cash generation. Caution: return on equity is only 8.2%, and debt data is not available.
Natera, Inc. NTRA
Natera grew revenue 35.9% last fiscal year, one of the fastest rates here, and has an opportunity score of 96. Caution: its operating margin was -10.7% and return on equity was -10.6%, so it is not yet profitable on those measures.
Agilent Technologies, Inc. A
Agilent Technologies shows an operating margin of 22.2%, a free cash flow margin of 17.2% and debt-to-equity of 0.56, which suggests strong profits and light debt. Caution: revenue growth of 6.7% is modest, and its opportunity score is only 43.
Labcorp Holdings Inc. LH
Labcorp Holdings grew revenue 7.2% and carries debt-to-equity of 0.79, a moderate level. Quality score is 78. Caution: its operating margin of 10.4% and gross margin of 28.9% are thinner than many peers on this list.
IDEXX Laboratories, Inc. IDXX
IDEXX Laboratories has the highest quality score here at 96, backed by an operating margin of 32.0%, a free cash flow margin of 27.5% and return on equity of 70.7%. Caution: its opportunity score is just 7, and growth was 10.4%.
CareDx, Inc CDNA
CareDx grew revenue 13.8% with an operating margin of 23.6% and return on equity of 26.1%, signs of a profitable, growing business. Caution: free cash flow, gross margin and debt figures are unavailable, and its quality score is a middling 62.
Guardant Health, Inc. GH
Guardant Health grew revenue 32.9% and has a gross margin of 65.0%, so growth is strong. Caution: its operating margin was -39.7% and free cash flow margin was -20.3%, meaning it is spending more than it earns, and its quality score is 51.
Danaher Corporation DHR
Danaher has an operating margin of 20.4%, a free cash flow margin of 21.8% and debt-to-equity of 0.53, a profitable, lightly indebted profile. Caution: revenue growth was only 2.9% and return on equity was 7.6%, both on the low side.
Mettler-Toledo International Inc. MTD
Mettler-Toledo has a gross margin of 60.3% and a free cash flow margin of 20.9%, with growth of 4.0%. Caution: debt-to-equity is very high at 159.45, its return on equity of 7062.4% is unusually large, and operating margin data is unavailable.
Thermo Fisher Scientific Inc. TMO
Thermo Fisher Scientific shows an operating margin of 17.6%, a free cash flow margin of 15.8% and debt-to-equity of 0.81, which reads as steady profitability with moderate debt. Caution: revenue growth was just 3.9%, and gross margin data is unavailable.
IQVIA Holdings Inc. IQV
IQVIA Holdings grew revenue 5.9%, with an operating margin of 13.2% and return on equity of 22.3%. Caution: debt-to-equity of 2.58 is higher than most peers on this list, and its margins are only moderate.
Sotera Health Company SHC
Sotera Health has a gross margin of 55.0% and return on equity of 24.6%, with revenue growth of 5.7%. Caution: debt-to-equity of 3.41 is the heaviest borrowing among the companies with that data, free cash flow margin is only 9.3%, and operating margin is unavailable.
Illumina, Inc. ILMN
Illumina has a gross margin of 66.4%, an operating margin of 19.6% and a free cash flow margin of 20.7%, so it is profitable. Caution: revenue changed by -0.7% last fiscal year, meaning no growth, and its opportunity score is 15.
Common questions
What do diagnostics and research companies do?
In general, these companies provide tests, lab services, instruments or research support used to detect, monitor and study disease. Some sell directly to patients and doctors, while others serve laboratories and drug researchers.
What do Marvin's Overall, quality and opportunity scores mean?
Overall is Marvin's summary score. Quality reflects how strong a company's business measures are, and opportunity is a separate score. All three compare a company with others in the same industry today and are not predictions.
Why do some companies on the list have negative margins?
Some fast-growing companies spend heavily on research and expansion, so their costs can exceed their revenue for a while. A negative margin means the company lost money on that measure in its latest fiscal year, so it carries more financial risk than a steadily profitable peer.
Keep reading
- Top 20 Medical Stocks Ranked by Marvin Scores
- Top 23 Stocks With Strong Momentum Right Now
- Top 15 Healthcare Stocks by Marvin Opportunity Score
- Top 15 Healthcare Companies With the Strongest Businesses
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Marvin's scores (0-100) compare each company with others in its industry today. Growth and margin figures come from SEC filings. This is general information, not personal investment advice or a recommendation to buy or sell anything. Do your own research.