Who Is Buying Merck? Hedge Fund Activity in 2026

Merck is a pharmaceutical titan whose fortunes are inextricably linked to Keytruda — the world's best-selling drug and an oncology blockbuster generating over $25 billion annually. At around $120.87 per share, MRK trades at a valuation that reflects both the enormous power of its current franchise and investor anxiety about Keytruda's patent cliff. The big question hanging over Merck is what comes after Keytruda — and hedge funds are answering with their wallets.

The latest 13F filings show one of the strongest buy signals in our tracking universe: 9 out of 17 funds are increasing their Merck positions, with several making massive additions.

Merck Institutional Snapshot

A 9-to-4 buy-sell ratio makes Merck one of the most institutionally favored pharmaceutical stocks right now. The breadth and scale of the buying is particularly impressive.

Who's Buying Merck?

The buying side features an extraordinary concentration of smart money capital:

Vanguard holds $30.7 billion and increased, maintaining its position as Merck's anchor institutional holder. State Street at $14.5 billion (increased) and Fidelity at $4.9 billion (increased) complete the big-three passive/active accumulation.

But the real story is the hedge fund buying, which is remarkable in both scale and breadth:

Appaloosa Management holds a staggering $1.4 billion position and increased. David Tepper's fund making a billion-dollar-plus commitment to a single pharma name is a high-conviction signal that few institutional moves can match.

Citadel increased to $824.5 million — a massive position for the multi-strategy giant that suggests conviction across multiple internal teams and strategies.

Millennium Management increased to an enormous $822 million. This is a huge position for a pod-based fund and indicates that multiple portfolio managers within Millennium independently see opportunity in Merck.

D.E. Shaw added to reach $425.3 million, the quantitative firm's models finding favorable signals in MRK's setup.

Whale Rock Capital increased its smaller $1.1 million position, adding another data point on the bullish side.

The combined hedge fund buying in Merck exceeds $3.4 billion across just four funds — a truly exceptional concentration of smart money conviction. This level of coordinated large-position building is rare in our tracking data and suggests that multiple independent research processes have arrived at similar bullish conclusions about Merck's prospects.

Who's Selling Merck?

The selling side is smaller but includes notable names:

Baker Bros Advisors holds $1.3 billion but decreased. The healthcare specialist's trim is the most concerning bearish signal, given Baker Bros' deep pharmaceutical expertise. Their reduction may reflect specific pipeline concerns or competitive analysis that broader market participants haven't yet appreciated.

Canyon Capital decreased its $625.4 million position, possibly rebalancing after strong Merck performance.

Bridgewater trimmed its $37.5 million position, a relatively small reduction from the macro-focused fund.

Two Sigma reduced to $9 million, a minimal position suggesting the quant firm has largely moved past its MRK thesis.

Notable Moves

The standout theme in Merck's 13F data is the sheer scale of hedge fund buying. Having Appaloosa ($1.4B), Citadel ($824.5M), and Millennium ($822M) all increasing massive positions simultaneously creates one of the strongest institutional buy signals we've ever tracked.

This isn't small positioning or exploratory capital — these are billion-dollar-scale commitments from three of the most sophisticated institutional investors in the world. When Appaloosa, Citadel, and Millennium agree on a pharma stock to this degree, the market should take notice.

The contrast with Baker Bros' decrease is worth considering, however. Baker Bros is arguably the most specialized healthcare investor in our universe, and their reduction creates an important counterpoint. Are the generalist mega-funds seeing something the specialist is missing — or is it the other way around?

What This Signals

The institutional picture for Merck is strongly bullish with a narrow but important exception:

The buy signal is overwhelming. Nine out of seventeen funds buying, anchored by three funds with $800M+ positions each, creates an exceptionally strong institutional consensus. This level of hedge fund agreement on a single pharmaceutical stock is rare and historically has been associated with meaningful subsequent returns.

The Keytruda calculus may be shifting. Merck's pipeline beyond Keytruda — including its oncology combinations, cardiovascular candidates, and the recently acquired assets — may be reaching an inflection point that institutional investors are positioning for. The scale of buying suggests sophisticated investors believe the post-Keytruda narrative is better than the market appreciates.

Baker Bros' dissent matters. The healthcare specialist reducing while generalist hedge funds pile in creates a tension worth monitoring. Baker Bros may have deeper pipeline intelligence or competitive insights that justify their caution. Then again, they may simply be taking profits after a good run.

Valuation offers entry. At $120.87, Merck trades at a reasonable multiple for a company with Keytruda's cash generation power. The institutional buying suggests the Keytruda patent cliff concern may be overdone relative to Merck's ability to extend the franchise and build new growth drivers.

The subcutaneous Keytruda extension could be transformative. Merck's development of a subcutaneous formulation of Keytruda could extend the franchise's patent protection and commercial life significantly. If successful, this would address the single biggest investor concern — the Keytruda patent cliff — and could explain why so many funds are aggressively building positions ahead of potential positive data readouts.

The pipeline diversification story is improving. Beyond Keytruda, Merck's cardiovascular program, pneumococcal vaccine franchise, and animal health division provide diversification that the market may be underappreciating. Institutional buyers at this scale typically look beyond single-product risk — their positioning suggests confidence in Merck's ability to sustain growth across multiple therapeutic areas.

Baker Bros' dissent warrants monitoring. While the overwhelming institutional consensus is bullish, completely ignoring a healthcare specialist's reduction would be imprudent. Track Baker Bros' position in the next filing to determine whether their trim was profit-taking or the beginning of a larger reduction.

For investors, Merck presents one of the clearest institutional buy signals in our pharmaceutical coverage. The smart money is not just buying — it's buying in size. The concentration of billion-dollar-scale positions from Appaloosa, Citadel, and Millennium makes this one of the most compelling institutional endorsements we've tracked.

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Track MRK institutional moves in real-time with Freenance Smart Money — we track 35 funds with $21.4T total AUM across 77,111 positions. See who's buying and selling at app.freenance.io/smart-money/ticker/MRK.

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FAQ

Why are hedge funds aggressively buying Merck (MRK) right now?

Funds like Appaloosa, Citadel, and Millennium are each holding $800M+ Merck positions, signaling rare alignment across fundamental, multi-strategy, and pod-based platforms. The likely thesis centers on Keytruda's continued cash generation combined with pipeline catalysts the broader market may be discounting too heavily.

What is the Keytruda patent cliff and how does it affect MRK?

Keytruda is Merck's oncology blockbuster generating over $25B annually, and its key patents begin expiring later this decade. The "patent cliff" describes the revenue risk as biosimilars enter — but institutional investors increasingly believe formulation extensions and pipeline diversification can offset much of that gap.

How important is Merck's oncology pipeline beyond Keytruda?

The pipeline includes Keytruda combination therapies, antibody-drug conjugates, and earlier-stage assets that could extend Merck's oncology franchise well past current patent expirations. Hedge funds at this scale typically aren't betting on one drug — they're modeling probability-weighted pipeline outcomes over multi-year horizons.

Why is Baker Bros reducing MRK while generalist hedge funds add?

Baker Brothers is one of the most specialized healthcare investors in the market, and their reduction stands out against the broad bullish consensus. This dissent could reflect deeper pipeline intelligence — or simply post-rally profit-taking — which is why tracking their next 13F filing is informative.

What role do Merck's vaccines and animal health businesses play in the thesis?

Beyond Keytruda, Merck operates a meaningful vaccines franchise (including Gardasil and pneumococcal candidates) and an animal health division that provides revenue diversification. Institutional buyers often cite this breadth as the reason single-product risk is overstated at current valuations.