NEW YORK ( TheStreet) -- Quest Diagnostics Inc (NYSE: DGX) is trading at unusually high volume Tuesday with 7.6 million shares changing hands. It is currently at 4.1 times its average daily volume and trading up $5.61 (+11%) at $56.59 as of 3:40 p.m. ET. Quest has a market cap of $7.9 billion and is part of the health care sector and health services industry. Shares are down 5.5% year to date as of the close of trading on Monday. Quest Diagnostics Incorporated provides diagnostic testing, information, and services in the United States and internationally. The company has a P/E ratio of 17.9, equal to the average health services industry P/E ratio and above the S&P 500 P/E ratio of 17.7. TheStreet Ratings rates Quest as a buy. The company's strengths can be seen in multiple areas, such as its revenue growth, expanding profit margins and increase in stock price during the past year. We feel these strengths outweigh the fact that the company has had sub par growth in net income. You can view the full Quest Ratings Report. See all heavy volume stocks in our stocks moving on unusual volume list or get investment ideas from our investment research center. Interested in other stocks that are rising on unusually high volume? Get free SMS text alerts sent to you when the action happens by texting HVUP to 95370 or select from multiple alert options.