MRSN vs ABBV vs MRK vs PFE

For growth investors, Mersana Therapeutics, Inc.

(MRSN) is the stronger pick with 9. 9% revenue growth year-over-year, versus -1. 6% for Pfizer Inc. (PFE). Merck & Co. , Inc. (MRK) offers the better valuation at 15. 4x trailing P/E (21. 9x forward), making it the more compelling value choice. Analysts rate Mersana Therapeutics, Inc. (MRSN) a "Buy" — based on 19 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.

On trailing P/E, Merck & Co.

, Inc. (MRK) is the cheapest at 15. 4x versus AbbVie Inc. at 85. 5x. On forward P/E, Pfizer Inc. is actually cheaper at 8. 9x — notably different from the trailing picture, reflecting expected earnings growth.

Over the past 5 years, AbbVie Inc.

(ABBV) delivered a total return of +101. 3%, compared to -92. 5% for Mersana Therapeutics, Inc. (MRSN). Over 10 years, the gap is even starker: ABBV returned +295. 5% versus MRSN's -91. 7%. Past returns do not guarantee future results, and the stock with the higher historical return may already have its best growth priced in.

By beta (market sensitivity over 5 years), AbbVie Inc.

(ABBV) is the lower-risk stock at 0. 34β versus Mersana Therapeutics, Inc. 's 2. 22β — meaning MRSN is approximately 556% more volatile than ABBV relative to the S&P 500. On balance sheet safety, Pfizer Inc. (PFE) carries a lower debt/equity ratio of 78% versus 96% for Merck & Co. , Inc. — giving it more financial flexibility in a downturn.

By revenue growth (latest reported year), Mersana Therapeutics, Inc.

(MRSN) is pulling ahead at 9. 9% versus -1. 6% for Pfizer Inc. (PFE). On earnings-per-share growth, the picture is similar: Mersana Therapeutics, Inc. grew EPS 61. 8% year-over-year, compared to -3. 5% for Pfizer Inc.. Over a 3-year CAGR, MRSN leads at 880. 2% 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.

Merck & Co.

, Inc. (MRK) is the more profitable company, earning 28. 1% net margin versus -170. 9% for Mersana Therapeutics, Inc. — meaning it keeps 28. 1% of every revenue dollar as bottom-line profit. Operating margin tells a similar story: MRK leads at 36. 2% versus -181. 1% for MRSN. At the gross margin level — before operating expenses — MRSN leads at 100. 0%, 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.

On forward earnings alone, Pfizer Inc.

(PFE) trades at 8. 9x forward P/E versus 21. 9x for Merck & Co. , Inc. — 13. 0x cheaper on a one-year earnings basis. Analyst consensus price targets imply the most upside for ABBV: 26. 6% to $256. 64.

In this comparison, PFE (6.

5% yield), ABBV (3. 2% yield), MRK (2. 9% yield) pay a dividend. MRSN does not pay a meaningful dividend and should not be held primarily for income.

For long-horizon retirement investors, AbbVie Inc.

(ABBV) is the stronger choice — it scores higher on the combination of lower volatility, dividend reliability, and long-term compounding (low volatility (β 0. 34), 3. 2% yield, +295. 5% 10Y return). Mersana Therapeutics, Inc. (MRSN) carries a higher beta of 2. 22 — meaning larger drawdowns in market downturns, which matters significantly when you cannot wait years for a recovery. Both have compounded well over 10 years (ABBV: +295. 5%, MRSN: -91. 7%), 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.

Both stocks operate in the Healthcare sector, making this a peer-level intra-sector comparison — the same macro tailwinds and headwinds will affect both.

In terms of investment character: MRSN is a small-cap quality compounder stock; ABBV is a large-cap income-oriented stock; MRK is a large-cap deep-value stock; PFE is a mid-cap income-oriented stock. ABBV, MRK, PFE pay a dividend while MRSN does not, making them suitable for different income and tax situations. 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.