Health care stocks were softer Tuesday afternoon, with the NYSE Health Care Index and the Health Care Select Sector SPDR Fund (XLV) both down 0.4%.

The iShares Biotechnology ETF (IBB) rose 0.5%.

In corporate news, Merck (MRK) issued a downbeat full-year outlook, overshadowing stronger-than-expected Q4 results. The shares fell past 10%.

Pfizer's (PFE) Q4 results topped market expectations amid double-digit revenue growth across key segments, while the pharmaceutical giant reiterated its full-year outlook. Its shares were down 1.7%.

Novartis (NVS) is on the hunt for next-generation obesity drug candidates, despite its main focus remaining on therapeutic areas where it has an established presence, The Wall Street Journal reported Tuesday, citing an interview with Chief Executive Vasant Narasimhan. Novartis shares were fractionally lower.