Healthcare stocks were lower Tuesday afternoon, with the NYSE Healthcare Index falling 1.1% and the State Street Health Care Select Sector SPDR ETF (XLV) shedding 0.9%.

The iShares Biotechnology ETF (IBB) rose 0.6%.

In corporate news, AbbVie (ABBV) and Merck (MRK) are facing investigations by the China Select Committee of the US House over whether clinical trials conducted in China may have contributed to the country's military capabilities, Reuters reported. AbbVie shares were down 0.6%, and Merck shed 0.7%.

Align Technology (ALGN) shares fell 2.9% after the European Commission said Tuesday it has opened an antitrust probe to determine whether the company has violated EU competition rules by tying its dental clear aligners to its intra-oral scanners in the European Economic Area.

PetMed Express (PETS) shares surged 10% after it said Tuesday it received an unsolicited, non-binding and conditional proposal from SilverCape Investments to buy the company for $3 per share in cash.