MRK GAAP Loss on $5.7B Terns Charge, 2026 Guidance Cut 47%

Merck (MRK) reported Q2 2026 revenue of $16.6 billion on August 4, up 5% year over year, but swung to a GAAP net loss of $(1,335) million, or $(0.54) per share. The culprit was a $5.7 billion charge for the Terns Pharmaceuticals acquisition, which more than doubled R&D expense to $9.7 billion for the quarter. Merck slashed its full-year 2026 non-GAAP EPS guidance to $2.66-$2.76, down from $5.04-$5.16. The $2.31 per share in combined Terns and Cidara acquisition costs explains the entire reduction. Shares closed at $128.00.

The numbers

• Ticker: MRK
• Stock price: $128.00 (close August 4)
• Q2 revenue: $16.6 billion (+5% YoY)
• GAAP EPS: $(0.54)
• Non-GAAP EPS: $(0.13)
• New 2026 guidance: $2.66-$2.76 (down from $5.04-$5.16)
• Keytruda: $8.37 billion (+5%)
• Winrevair: $588 million (+75%)
• Ohtuvayre: $204 million (new, from Verona Pharma acquisition)

The cost of transformation

The Terns acquisition closed in early 2026, adding TERN-701, a novel allosteric BCR-ABL inhibitor for chronic myeloid leukemia. The Cidara deal added another $9.0 billion in one-time R&D charges. Together these transactions produced $2.31 per share in acquisition-related costs this quarter.

R&D expense hit $9.7 billion, compared with roughly $4 billion in the prior-year quarter. The spending reflects Merck’s pivot away from Keytruda dependence. Keytruda’s $8.37 billion in Q2 sales still represents roughly 50% of total revenue, and the drug loses US patent protection in 2028. With biosimilar competition expected soon after, Merck is racing to build new revenue streams that can replace a product generating over $30 billion annually.

Winrevair (sotatercept), Merck’s pulmonary arterial hypertension drug approved in March 2024, grew 75% to $588 million. PAH affects an estimated 30,000 to 50,000 US patients, and Winrevair now holds a dominant position as the first activin signaling inhibitor in the class. Ohtuvayre (ensifentrine), a first-in-class PDE3/PDE4 inhibitor for COPD obtained through the $10.4 billion Verona Pharma acquisition, contributed $204 million in its second full quarter. COPD affects roughly 16 million diagnosed US adults.

What to watch

The near-term risk is execution. Merck is simultaneously integrating two multi-billion-dollar acquisitions while advancing registrational programs for several acquired assets. If Winrevair’s growth stalls or Ohtuvayre’s COPD launch underwhelms, the post-Keytruda math gets harder. On the upside, Merck’s I-DXd B7-H3 ADC had faced an October 10 PDUFA date in small cell lung cancer, but Merck and Daiichi Sankyo withdrew the BLA on September 25 after the FDA said the Phase 2 data do not support accelerated approval (see our withdrawal coverage).

Merck Q2 2026 press release

What It Means for the Trade

Parse the noise first: the GAAP loss and the guidance cut are accounting artifacts, not operational deterioration. The $5.7 billion Terns charge and the $9.0 billion Cidara charge are one-time, cash-free write-downs of acquired intangibles — the real price of those deals was paid at closing. Non-GAAP EPS of $(0.13) includes the same items stripped of amortization; strip the $2.31 of deal costs entirely and the underlying quarter was solid (revenue +5%, Keytruda +5%, Winrevair +75%). The market understood this — the stock closed at $128.00, roughly flat-to-firm on the print. Traders who sold the “guidance cut 47%” headline without reading the bridge sold an accounting entry.

The story worth trading is the race clock. Keytruda is ~50% of revenue at $8.37 billion a quarter, U.S. patent protection ends 2028, and biosimilars are queued. The acquisitions (Terns for TERN-701 in CML, Cidara for antifungal assets, Verona for Ohtuvayre) plus the organic pipeline (Winrevair, Enflonsia, I-DXd, sac-TMT from Kelun) are Merck’s attempt to build a post-Keytruda revenue stack roughly $15-20 billion deep before the cliff. Q2’s numbers say the building is going well — Winrevair annualizing toward $2.5 billion-plus, Ohtuvayre’s $204 million in only its second full quarter implies a ~$800 million-plus run-rate with the COPD market wide open — but the clock is unforgiving: 2026-2027 launches must compound at or above plan for the 2029 transition to be smooth.

The cleanest near-term catalyst just fell off the calendar: the October 10 I-DXd PDUFA in SCLC was removed when Merck and Daiichi Sankyo withdrew the BLA on September 25. A B7-H3 ADC approval would have opened a second oncology franchise lane (behind Keytruda, alongside sac-TMT’s buildup); that proof now waits on the Phase 3 IDeate-Lung02 readout.

Deal Logic Context: What Merck Bought

Worth being specific about the acquisition targets, because the pattern reveals the strategy. Terns brought TERN-701, an allosteric (non-ABL-binding) BCR-ABL inhibitor for chronic myeloid leukemia — a market dominated by Novartis’ Tasigna/Gleevec lineage where ponatinib’s vascular toxicity and asciminib’s partial coverage leave room for a cleaner pan-mutant inhibitor, including the T315I-compound mutation territory. Cidara’s antifungal franchise (rezafungin and assets behind it) is steady mid-market infectious-disease revenue with hospital-channel stickiness. Verona’s Ohtuvayre is the crown jewel of the three — first-in-class dual PDE3/PDE4 inhalable bronchodilator/anti-inflammatory for COPD, a $10 billion-plus market with no new mechanism in decades, launched at a ~$1 billion-plus first-year pace that supports the $10.4 billion price.

The pattern: none of these are moonshots. All three are late-stage or launched assets with definable commercial timelines — Merck is buying revenue certainty, not pipeline lottery tickets. That’s the right posture for a company whose problem isn’t science, it’s a dated revenue mix. The contrast with Lilly’s mechanism-platform bets (Merida, AtaiBeckley) is instructive: Lilly can afford decade-horizon optionality; Merck needs 2027-2030 cash flows.

Risks and What Could Go Wrong

(1) Keytruda erosion dynamics. The 2028 U.S. cliff is priced, but the composition-of-matter defense (subcutaneous Keytruda, KEYTRUDA-QLEX) only softens it; if EU/Japan biosimilar pressure arrives earlier or SC conversion underperforms, the replacement burden grows. (2) Winrevair ceiling risk. The 75% growth is off a small base in a 30,000-50,000 patient indication — if penetration plateaus at $3 billion rather than the $5 billion-plus bulls model, the stack comes up short. (3) Ohtuvayre launch execution in a primary-care-adjacent market. COPD prescribing runs through pulmonology but volume through GPs; payer coverage and nebulizer-channel logistics are untested at Verona scale. (4) Integration load. Two multi-billion integrations running simultaneously plus a dozen-plus business-development streams is where big pharma historically drops balls — watch for pipeline triage announcements that quietly shelve acquired programs. (5) The I-DXd withdrawal. The September 25 BLA withdrawal removes the nearest-term catalyst and refocuses attention on sac-TMT data and the 2027 gap.

Position sensibly: MRK at $128 is a modest-multiple, high-dividend mega-cap with a well-telegraphed transition — the trade is in the catalyst cadence (sac-TMT data, Winrevair trajectory, the IDeate-Lung02 readout), not the quarterly GAAP theater.