01:37 PM EDT, 09/29/2025 (MT Newswires) -- Health care stocks were edging down Monday afternoon, with the NYSE Health Care Index and the Health Care Select Sector SPDR Fund (XLV) fractionally lower.

The iShares Biotechnology ETF (IBB) added 0.5%.

In corporate news, MoonLake Immunotherapeutics ( MLTX ) shares tumbled 89% following the release of data from its late-stage trials in hidradenitis suppurativa, a chronic inflammatory skin disease, that led several analysts to downgrade the stock.

Genmab ( GMAB ) has agreed to buy Merus (MRUS) in an all-cash deal worth about $8 billion, the companies said. Genmab ( GMAB ) shares were down 0.3%, and Merus surged 36%.

AbbVie ( ABBV ) shares eased 0.1% after it said Monday that it has begun constructing its new active pharmaceutical ingredient manufacturing plant in North Chicago, Illinois. The facility is a part of AbbVie's ( ABBV ) more than $10 billion investment plan in the US to expand its manufacturing footprint, the company said.