MRK's Keytruda & Gardasil Sales Rise in Q3: Can the Momentum Last?

In Q3 2026, Merck’s combined Keytruda and Keytruda Qlex sales rose 6% to $8.60 billion; Keytruda excluding Qlex reached $7.77 billion, above the $7.46 billion consensus. Gardasil sales rose 14% to $1.99 billion, also beating estimates, but about $300 million of favorable U.S. purchasing benefits—not broad-based demand recovery—supported the quarter; $50 million is expected to reverse in Q4 2026 and $250 million in 2027. Merck expects growth headwinds from Keytruda’s peak penetration and U.S. biosimilar entry beginning in 2028, while Gardasil faces weak Asian demand and competition. Merck shares were up 42.9% year to date, versus 22.7% for the industry; the company has a Zacks Rank #3 (Hold).

Analysis

The key issue is earnings quality, not Q3 growth: both franchises received temporary U.S. channel support, so reported momentum risks pulling demand forward into Q4 and 2027. That creates a tougher comparison precisely as Gardasil faces weaker overseas demand and cheaper Chinese competition. For Keytruda, earlier-stage uptake extends the commercial runway, but peak penetration in some indications and 2028 U.S. exclusivity loss make growth increasingly dependent on new uses, launch execution and formulation mix. Keytruda Qlex may soften exposure to the original IV product only if conversion, uptake and economics prove durable; the article does not establish that.

Near term, watch Q4 sales and channel inventory: reversals could expose underlying demand before the longer-term patent issue is priced. Over 1–3 months, guidance and 2027 franchise commentary are the catalysts. Over 6–18 months, the central risk is a valuation reset if Gardasil normalizes downward while Keytruda growth moderates ahead of biosimilar entry. Merck’s large share rally increases sensitivity to any miss, but does not by itself establish overvaluation.

A relative-value angle is to favor AstraZeneca over Merck if subsequent results confirm continued Imfinzi momentum alongside Merck’s normalization; this is a conditional thesis, not a direct read-through from non-comparable periods. Falsifiers include sustained Gardasil end-demand recovery, Keytruda growth holding up after inventory unwinds, or evidence Qlex meaningfully offsets IV erosion. The article supplies no valuation or consensus detail sufficient to justify a price target.

Key Decisions for Investors

• Avoid chasing Merck on the Q3 beat; consider reducing exposure or using a defined-risk bearish options structure into Q4 only if price action fails to reflect the expected channel reversals. Reassess on reported sales and management’s 2027 outlook.
• Set an alert for Merck’s next results: separate underlying Keytruda demand from inventory effects and track Gardasil U.S. purchasing versus vaccination demand, China/Japan trends, and net pricing.
• Consider a conditional long AstraZeneca / short Merck pair over 3–12 months, sized conservatively and initiated only if AstraZeneca sustains Imfinzi growth while Merck confirms moderation. Close or reassess if Merck’s post-inventory growth holds up or AstraZeneca’s momentum weakens.
• Monitor Keytruda Qlex uptake and the mix of IV versus Qlex sales; without evidence that the newer formulation can offset the approaching IV exclusivity pressure, do not treat it as a proven hedge.