Sifting through countless of stocks in the Life Sciences Tools & Services industry can be tedious, and sometimes two stocks are just too similar to judge which is the better investment. If you’re on the fence about investing in Thermo Fisher Scientific Inc. or Repligen Corporation because you’re not sure how they measure up, it’s important to compare them on a few factors before making your decision.

Read on to learn how Thermo Fisher Scientific Inc. and Repligen Corporation compare based on key financial metrics to determine which better meets your investment needs.

About Thermo Fisher Scientific Inc. and Repligen Corporation

Thermo Fisher Scientific Inc. provides life sciences solutions, analytical instruments, specialty diagnostics, and laboratory products and biopharma services internationally. It operates through four segments: Life Sciences Solutions, Analytical Instruments, Specialty Diagnostics, and Laboratory Products and Biopharma Services. The Life Sciences Solutions segment includes reagents, instruments, and consumables for biological and medical research; discovery and production of drugs and vaccines; and diagnosis of infections and diseases. Its Analytical Instruments segment provides instruments, consumables, software, and services for pharmaceutical, biotechnology, academic, government, environmental, and other research and industrial markets, as well as clinical laboratories. The Specialty Diagnostics segment offers clinical diagnostics products, such as liquid ready-to-use and lyophilized immunodiagnostic reagent kits, calibrators, controls, protein detection assays, and instruments; immunodiagnostic offerings comprising developing, manufacturing, and marketing of complete blood-test systems for the clinical diagnosis and monitoring of allergy, asthma and autoimmune diseases; microbiology offerings, such as dehydrated and prepared culture media, collection and transport systems, instrumentation and consumables to detect pathogens in blood, diagnostic and rapid direct specimen tests, quality-control products, and associated products; transplant diagnostics products, including human leukocyte antigen typing and testing for the organ transplant market; and healthcare market channel offerings. Its Laboratory Products and Biopharma Services segment provides laboratory products, research and safety market channel, and pharma services and clinical research. Thermo Fisher Scientific Inc. was founded in 1956 and is headquartered in Waltham, Massachusetts.

Repligen Corporation, a life sciences company, develops and commercializes bioprocessing technologies and systems in North America, Europe, the Asia Pacific, and internationally. The company’s products include hollow fiber consumables, KRM chromatography system, resins for new modalities, PATsmart MAVERICK and PATsmart MAVEN for real-time monitoring and control of critical bioprocess parameters, PATsmart REBEL, an at-line cell culture media analyzer; and PATsmart ZipChip, a high-resolution sample separations device, PATsmart SoloVPE slope spectroscopy system, and SoloVPE PLUS System. It offers Protien A ligands that are the binding components of Protein A affinity chromatography resins; and cell culture growth factor products. The company also provides chromatography products, including OPUS pre-packed chromatography columns, which are used in the purification and quality control of biological drugs, as well as ELISA test kits. In addition, it offers filtration products, such as XCell ATF Cell Retention Systems that are filtration devices used in upstream perfusion and cell culture processing; TangenX flat sheet cassettes, which are used in downstream biologic drug concentration, buffer exchange, and formulation processes; KrosFlo tangential flow filtration and tangential flow depth filtration systems; and ProConnex TFDF flow paths. Further, it provides process analytics products, such as slope spectroscopy systems. The company offers its products under the OPUS, XCell, XCell ATF, TFDF, KrosFlo, SIUS, ProConnex, Spectra/Por, NGL-Impact, SoloVPE, FlowVPE, RPM, XO, Metenova MixOne, and AVIPure and FlowVPX brands. The company sells its products to life sciences, biopharmaceutical, and diagnostics companies; laboratory researchers; and contract manufacturing organizations. Repligen Corporation has a collaboration agreement with Navigo Proteins GmbH to develop multiple affinity ligands. The company was incorporated in 1981 and is headquartered in Waltham, Massachusetts.

Latest Life Sciences Tools & Services and Thermo Fisher Scientific Inc., Repligen Corporation Stock News

As of August 21, 2026, Thermo Fisher Scientific Inc. had a $232.7 billion market capitalization, compared to the Life Sciences Tools & Services median of $3.0 million. Thermo Fisher Scientific Inc.’s stock is up 8.6% in 2026, up 7% in the previous five trading days and up 27.17% in the past year.

Currently, Thermo Fisher Scientific Inc.’s price-earnings ratio is 33.9. Thermo Fisher Scientific Inc.’s trailing 12-month revenue is $46.3 billion with a 15.0% net profit margin. Year-over-year quarterly sales growth most recently was 10.5%. Analysts expect adjusted earnings to reach $25.118 per share for the current fiscal year. Thermo Fisher Scientific Inc. currently has a 0.3% dividend yield.

As of August 21, 2026, Repligen Corporation had a $10.2 billion market cap, putting it in the 78th percentile of all stocks. Repligen Corporation’s stock is up 10.5% in 2026, up 8.6% in the previous five trading days and up 49.01% in the past year.

Currently, Repligen Corporation’s price-earnings ratio is 248.1. Repligen Corporation’s trailing 12-month revenue is $785.1 million with a 5.3% net profit margin. Year-over-year quarterly sales growth most recently was 11.9%. Analysts expect adjusted earnings to reach $2.064 per share for the current fiscal year. Repligen Corporation does not currently pay a dividend.

How We Compare Thermo Fisher Scientific Inc. and Repligen Corporation Stock Grades

Stock evaluation requires access to huge amounts of data and the knowledge and time to sift through it all, make sense of financial ratios, read income statements and analyze recent stock movements. AAII created A+ Investor, a robust data suite that condenses data research in an actionable and customizable way suitable for investors of all knowledge levels, to help investors streamline and work through such data.

AAII’s proprietary stock grades come with A+ Investor. These offer intuitive A‐F grades for each of five key investing factors: value, growth, momentum, earnings estimate revisions and quality. Here, we’ll take a closer look at Thermo Fisher Scientific Inc. and Repligen Corporation’s stock grades to see how they measure up against one another.

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Thermo Fisher Scientific Inc. and Repligen Corporation’s Quality Grades

Company	Ticker	Quality
Thermo Fisher Scientific Inc.	TMO	B
Repligen Corporation	RGEN	B

Like the Value Grade, AAII’s A+ Investor Quality Grade comes from the percentile rank of key metrics. Specifically, the Quality Score is the percentile rank of the average of the percentile ranks of return on assets (ROA), return on invested capital (ROIC), gross profit relative to assets, buyback yield, change in total liabilities to assets, accruals, Z double prime bankruptcy risk (Z) score and the F-Score.

The score is variable, meaning it can consider all eight measures or, should any of the eight measures not be valid, the remaining measures that are valid. To be assigned a Quality Score, stocks must have a valid (non-null) measure and corresponding ranking for at least four of the eight quality measures.

The Quality Score is used to assess the underlying “quality” of a particular stock. A higher-quality stock possesses traits associated with upside potential and reduced downside risk. Backtesting of the Quality Grade shows that stocks with higher grades, on average, outperformed stocks with lower grades over the period of 1998 through 2019.

Stocks receive better grades (higher scores) for having higher scores for the quality subcomponents and worse grades (lower scores) for lower scores for the subcomponents.

Thermo Fisher Scientific Inc. has a Quality Score of 65, which is Strong. Repligen Corporation has a Quality Score of 67, which is Strong.

The Quality Grade Winner: It’s a Tie!

Looking at the Quality Grade breakdown above, both Thermo Fisher Scientific Inc. and Repligen Corporation have a grade of B. For investors who focus solely on a company’s overall quality, you will need to conduct further research into both companies to see if they are a good fit for your portfolio. As a good rule of thumb, you should always analyze multiple factors based on a wide range of metrics before choosing a company to invest in.

Thermo Fisher Scientific Inc. and Repligen Corporation’s Momentum Grades

Company	Ticker	Momentum
Thermo Fisher Scientific Inc.	TMO	A
Repligen Corporation	RGEN	A

Momentum grades help to uncover stocks experiencing anomalously high rates of return; research finds that stocks with high relative levels of momentum tend to outperform, whereas those with low levels of momentum tend to continue underperforming. Momentum is based on the price change of a stock over a specified period relative to all other stocks.

Typically, AAII looks at the weighted relative strength over the trailing four quarters. The weighted four-quarter relative strength rank is the relative price change for each of the past four quarters. The most recent quarterly price change is given a weight of 40% and each of the three previous quarters are given a weighting of 20%.

Thermo Fisher Scientific Inc. has a Momentum Score of 82, which is Very Strong. Repligen Corporation has a Momentum Score of 90, which is Very Strong.

The Momentum Grade Winner: It’s a Tie!

Looking at the Momentum Grade breakdown above, both Thermo Fisher Scientific Inc. and Repligen Corporation have a grade of A. For those who focus solely on a company’s momentum, further research will need to be conducted into both companies to see if they fit your individual needs as an investor.

Thermo Fisher Scientific Inc. and Repligen Corporation’s Estimate Revisions Grades

Company	Ticker	Earnings Estimate
Thermo Fisher Scientific Inc.	TMO	B
Repligen Corporation	RGEN	B

Earnings estimate revisions scores consider the magnitude of a company’s earnings surprise in its last two reported fiscal quarters. Often, positive surprises beget further positive surprises‐or at least continued sales growth (the exact opposite is generally true, too).

Estimate revisions offer an indication of what analysts are thinking about the short-term prospects of a firm. Estimate revisions are based on the statistical significance of a firm’s last two quarterly earnings surprises and the percentage change in its consensus estimate for the current fiscal year over the past month and past three months.

Thermo Fisher Scientific Inc. has a Earnings Estimate Score of 69, which is Positive. Repligen Corporation has a Earnings Estimate Score of 74, which is Positive.

The Earnings Estimate Revisions Grade Winner: It’s a Tie!

Looking at the Earnings Estimate Revisions Grade breakdown above, both Thermo Fisher Scientific Inc. and Repligen Corporation have a grade of B. For those focusing solely on a company’s estimate revisions, other financial metrics will need to be evaluated to determine whether Thermo Fisher Scientific Inc. or Repligen Corporation is a better fit.

Other Thermo Fisher Scientific Inc. and Repligen Corporation Grades

In addition to Momentum, Quality and Estimate Revisions, A+ Investor also provides grades for Value and Growth.

Growth investing builds on the idea that stocks of companies exhibiting strong, consistent and prolonged growth outperform those of slower-growth companies. AAII measures growth through consistency of annual sales growth, five-year sales growth rankings adjusted for extreme levels, and consistency of positive annual cash from operations.

Successful stock investing involves buying low and selling high, so stock valuation is an important consideration for stock selection. Buying stocks that are going to go up typically means buying stocks that are undervalued in the first place, although momentum investors may argue that point.

These 2 key factors, when combined with the above, provide a holistic view into a particular stock. Further, by joining A+ Investor you can see whether Thermo Fisher Scientific Inc. and Repligen Corporation pass any of our 60+ stock screens that have outperformed the market since their creation.

So, Which Is the Better Investment, Thermo Fisher Scientific Inc. or Repligen Corporation Stock?

Overall, Thermo Fisher Scientific Inc. stock has a Momentum Score of 82, Estimate Revisions Score of 69 and Quality Score of 65.

Repligen Corporation stock has a Momentum Score of 90, Estimate Revisions Score of 74 and Quality Score of 67.

Comparing Thermo Fisher Scientific Inc. and Repligen Corporation’s grades, scores and metrics can act as a solid basis to determine whether they may be a good investment or not. You’ll also want to look at your portfolio’s asset allocation as well as your risk tolerance and financial goals to see if either of these stocks would make a good fit for you. AAII can help you figure out which investments align with your individual needs and preferences.

Investors are encouraged to do their own due diligence and research. In this way, individuals can effectively become managers of their own assets‐without having to rely on others for financial independence. You can count on AAII for timeless articles on financial planning and stock-picking, unbiased research and actionable analysis.

A+ Investor adds to our qualitative teaching with a powerful data suite to help you whittle down investment choices to find stocks, exchange-traded funds (ETFs) or mutual funds that meet your needs.

AAII Disclaimer

We make no representations or warranties that any investor will, or is likely to, achieve profits similar to those shown, because past, hypothetical or simulated performance is not necessarily indicative of future results. Before making an investment decision, you should consider your circumstances and whether the information on our content is applicable to your situation. This information was prepared in good faith, and we accept no liability for any errors or omissions. The full disclaimer can be read here.