Merck & Co. (MRK): Investor Event Highlights Emerging HIV Portfolio

Research evidence excerpt

Merck & Co. (MRK): Investor Event Highlights Emerging HIV Portfolio

Equity Research

3 August 2026 | 2:10PM EDT

On the back of presenting updates across its emerging HIV portfolio at the Asad Haider, CFA

+1(212)902-0691 | asad.haider@gs.com

International AIDS conference, MRK held an investor event highlighting the data and Goldman Sachs & Co. LLC

its broader HIV portfolio strategy. MRK is returning in earnest to the ~$30bn+ HIV Nick Jennings

market (~$26bn treatment, ~$4bn prevention/PrEP) with an emerging portfolio of +1(415)249-7412nick.jennings@gs.com|

four key programs, which our KOL diligence suggests is underappreciated. Goldman Sachs & Co. LLC

Jeff Su

Most notably, two Ph3 trials for its GILD partnered once weekly HIV treatment +1(212)357-9930Goldman Sachs & Co.| jeff.su@gs.comLLC

islatravir plus lenacapavir (ISL/LEN) met the primary endpoint of non-inferior

efficacy at week 48, with high viral suppression rates with no treatment-emergent

resistance detected to either agent and a safety/tolerability profile comparable to

comparator arms. Additionally, Ph2 data for MRK’s wholly-owned once-weekly

treatment islatravir plus ulonivirine (ISL/ULO) was also positive, supporting

advancement into Ph3, and MRK is pleased with the launch progress of recently

approved daily oral treatment Idvynso. On the PrEP side, monthly oral alimatravir

Ph3 readouts are tracking for 2027.

Overall we model a total of ~$5bn unadjusted/ ~$3.4bn risk-adjusted (approximately

in-line with Visible Alpha Consensus Data) at peak for the emerging HIV portfolio,

which is aligned with MRK’s framing of >$5bn non-risk-adjusted opportunity by the

mid-2030s. We model a breakdown consisting of $3bn combined for the two weekly

oral treatments (partnered and proprietary), $1.5bn for oral monthly PrEP and