NEW YORK ( TheStreet) -- DexCom (Nasdaq: DXCM) is trading at unusually high volume Thursday with 1.4 million shares changing hands. It is currently at four times its average daily volume and trading down $1.38 (-8.4%) at $15.04 as of 12:36 p.m. ET. DexCom has a market cap of $1 billion and is part of the health care sector and health services industry. Shares are up 20.3% year to date as of the close of trading on Wednesday. DexCom, Inc., a medical device company, engages in the design, development, and commercialization of continuous glucose monitoring systems for people with diabetes in the United States. TheStreet Ratings rates DexCom as a sell. Among the areas we feel are negative, one of the most important has been weak operating cash flow. You can view the full DexCom 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 falling on unusually high volume? Get free SMS text alerts sent to you when the action happens by texting HVDOWN to 95370 or select from multiple alert options.