NEW YORK ( TheStreet) -- NxStage Medical Incorporated (Nasdaq: NXTM) is trading at unusually high volume Tuesday with 1.6 million shares changing hands. It is currently at four times its average daily volume and trading down $2.28 (-10.1%) at $20.30 as of 3:26 p.m. ET. NxStage Medical has a market cap of $1.1 billion and is part of the health care sector and health services industry. Shares are down 9.2% year to date as of the close of trading on Friday. NxStage Medical, Inc., a medical device company, engages in the development, manufacture, and marketing of products for the treatment of kidney failure, fluid overload, and related blood treatments and procedures in the United States. TheStreet Ratings rates NxStage Medical as sell. The area that we feel has been the company's primary weakness has been its disappointing return on equity. You can view the full NxStage Medical Ratings Report. See all heavy volume stocks in our stocks moving on unusual volume list or get investment ideas from our investment research center.