Sifting through countless of stocks in the Pharmaceuticals 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 GSK plc, Merck & Co. or Inc. 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 GSK plc, Merck & Co. and Inc. compare based on key financial metrics to determine which better meets your investment needs.

About GSK plc, Merck & Co. and Inc.

GSK plc, together with its subsidiaries, engages in the research, development, and manufacture of vaccines, specialty medicines, and general medicines to prevent and treat disease in the United Kingdom, the United States, and internationally. It operates through Commercial Operations and Total R&D segments. The company offers specialty medicines that include oncology, respiratory/immunology, inflammation, and inhaled medicines for HIV, respiratory eosinophildriven diseases, lupus and lupus nephritis, ovarian cancer, and endometrial cancer. It also provides vaccines for Shingles, Meningitis, RSV, Seasonal Influenza, Hepatitis, Diphtheria, Tetanus, Acellular Pertussis, Rotavirus, Pertussis, Polio, Haemophilus, Invasive Diseases, Pneumonia, Acute Otitis Media, Measles, Mumps, Rubella and Chickenpox, and Human Papilloma Virus. Additionally, the company offers general medicines for asthma, COPD, bacterial infection, benign prostatic hyperplasia, allergic rhinitis, and inflammatory skin conditions. It also focuses on the discovery, development, and commercialization of oral small molecule therapies for patients with unmet needs in oncology and inflammatory diseases. It has a collaboration agreement with CureVac to develop mRNA vaccines for infectious diseases; and strategic research collaboration with Engitix Ltd. to identify and validate novel therapeutic targets driving liver fibrosis regression. The company has a strategic alliance with AN2 Therapeutics, Inc. for the development of new therapies for TB. GSK plc was formerly known as GlaxoSmithKline plc and changed its name to GSK plc in May 2022. The company was founded in 1715 and is headquartered in London, United Kingdom.

Merck & Co., Inc. operates as a healthcare company worldwide. It offers human health pharmaceutical for various areas under the Keytruda, Keytruda Qlex, Welireg, Gardasil, ProQuad, M-M-R II, Varivax, Vaxneuvance, Capvaxive, RotaTeq, Pneumovax 23, Bridion, Prevymis, Dificid, Zerbaxa, Winrevair, Adempas/ Verquvo, Ohtuvayre, Lagevrio, Isentress/Isentress HD, Delstrigo, Pifeltro, Belsomra, Januvia, and Janumet brands. The company also provides veterinary pharmaceuticals, vaccines and health management solutions and services, such as livestock products under the Nuflor, Bovilis/Vista, Bovilis Cryptium, Banamine, Estrumate, Matrix, Resflor, Zuprevo, Revalor, Safe-Guard, M+Pac, Porcilis, Circumvent, Nobilis/Innovax, Paracox and Coccivac, Exzolt, Slice, Imvixa, Clynav, Aquavac/Norvax, Aquaflor, Flexolt brands; Allflex Livestock Intelligence solutions; and companion animal products under the Bravecto One-Month, Bravecto Injectable/Quantum, Bravecto TriUNO, Bravecto Plus, Sentinel Spectrum, Sentinel Flavor Tabs, Numelvi, Optimmune, Nobivac NXT, GilvetMab, Otomax, Mometamax, Mometamax Ultra, Posatex, Caninsulin/Vetsulin, Panacur, Safeguard, Regumate, Prestige, Scalibor/Exspot, Sure Petcare, and Home Again brands. It has development and commercialization agreement for three of Daiichi Sankyo’s deruxtecan ADC candidates; AstraZeneca PLC to co-development and co-commercialize AstraZeneca’s Lynparza products for multiple cancer types; licensed to develop, manufacture and commercialize LM-299, a novel investigational PD-1/VEGF bispecific antibody from LaNova; and collaboration agreement with Eisai Co., Ltd., Bayer AG, and Ridgeback Biotherapeutics LP, as well Moderna, Inc. Merck & Co., Inc. has strategic collaboration with Infinimmune, Inc. to discover and develop antibodies against multiple therapeutic targets. The company was founded in 1891 and is headquartered in Rahway, New Jersey.

Latest Pharmaceuticals and GSK plc, Merck & Co., Inc. Stock News

As of September 4, 2026, GSK plc had a $99.7 billion market capitalization, compared to the Pharmaceuticals median of $672.4 million. GSK plc’s stock is NA in 2026, NA in the previous five trading days and up 25.95% in the past year.

Currently, GSK plc’s price-earnings ratio is 31.9. GSK plc’s trailing 12-month revenue is $44.1 billion with a 14.5% net profit margin. Year-over-year quarterly sales growth most recently was 2.0%. Analysts expect adjusted earnings to reach $4.790 per share for the current fiscal year. GSK plc currently has a 3.6% dividend yield.

Currently, Merck & Co., Inc.’s price-earnings ratio is 118.1. Merck & Co., Inc.’s trailing 12-month revenue is $66.6 billion with a 4.8% net profit margin. Year-over-year quarterly sales growth most recently was 5.1%. Analysts expect adjusted earnings to reach $2.748 per share for the current fiscal year. Merck & Co., Inc. currently has a 2.3% dividend yield.

How We Compare GSK plc, Merck & Co. and Inc. 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 GSK plc, Merck & Co. and Inc.’s stock grades to see how they measure up against one another.

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GSK plc, Merck & Co. and Inc. Growth Grades

Company	Ticker	Growth
GSK plc	GSK	A
Merck & Co., Inc.	MRK	A

The foundation of growth investing is seeking out stocks of companies exhibiting strong, consistent and prolonged growth that is expected to continue into the future.

In order to compute the growth score and assign it a letter grade, the percentile ranks for each of three components‐consistency of annual sales growth, five-year sales growth rankings adjusted for extreme levels, and consistency of positive annual cash from operations‐must be determined. These three rank figures are added together, and the sum is ranked against the entire stock universe to arrive at a company’s Growth Score to create an equal distribution of grades.

The companies in the bottom 20% of the stock universe receive Growth Grades of F, considered to be very weak, while those in the top 20% receive A grades, which are considered very strong.

GSK plc has a Growth Score of 100, which is Very Strong. Merck & Co., Inc. has a Growth Score of 100, which is Very Strong.

The Growth Grade Winner: It’s a Tie!

Looking at the Growth Grade breakdown above, both GSK plc, Merck & Co. and Inc. have a grade of A. For investors who focus solely on a company’s upward growth, further research should be conducted into both companies’ other financial metrics before deciding whether to invest.

GSK plc, Merck & Co. and Inc.’s Quality Grades

Company	Ticker	Quality
GSK plc	GSK	A
Merck & Co., Inc.	MRK	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.

GSK plc has a Quality Score of 98, which is Very Strong. Merck & Co., Inc. has a Quality Score of 80, which is Strong.

The Quality Grade Winner: GSK plc

As you can clearly see from the Quality Grade breakdown above, GSK plc has a better overall quality grade than Merck & Co., Inc.. For investors who are looking for companies with higher quality than others in the same industry, GSK plc could be a good stock to add to their portfolios. However, it’s important for investors to analyze multiple factors based on a wide range of metrics before deciding whether to buy.

GSK plc, Merck & Co. and Inc.’s Momentum Grades

Company	Ticker	Momentum
GSK plc	GSK	C
Merck & Co., Inc.	MRK	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%.

GSK plc has a Momentum Score of 54, which is Average. Merck & Co., Inc. has a Momentum Score of 86, which is Very Strong.

The Momentum Grade Winner: Merck & Co., Inc.

As you can clearly see from the Momentum Grade breakdown above, Merck & Co., Inc. is considered to have stronger momentum compared to GSK plc. For those specifically looking for companies that have stronger momentum compared to other companies in the same industry, Merck & Co., Inc. could be a good stock to invest in. However, it’s important for investors to analyze multiple factors based on a wide range of metrics before deciding whether to buy.

Other GSK plc, Merck & Co. and Inc. Grades

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

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

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 GSK plc, Merck & Co. and Inc. pass any of our 60+ stock screens that have outperformed the market since their creation.

So, Which Is the Better Investment, GSK plc, Merck & Co. or Inc. Stock?

Overall, GSK plc stock has a Growth Score of 100, Momentum Score of 54 and Quality Score of 98.

Merck & Co., Inc. stock has a Growth Score of 100, Momentum Score of 86 and Quality Score of 80.

Comparing GSK plc, Merck & Co. and Inc.’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.