NEW YORK ( TheStreet) -- XenoPort (Nasdaq: XNPT) is trading at unusually high volume Friday with 3.4 million shares changing hands. It is currently at four times its average daily volume and trading down 47 cents (-4.7%) at $9.49 as of 1:57 p.m. ET. XenoPort has a market cap of $225 million and is part of the health care sector and drugs industry. Shares are up 16.9% year to date as of the close of trading on Thursday. XenoPort, Inc., a biopharmaceutical company, focuses on developing internally discovered product candidates that utilize the body's natural nutrient transport mechanisms to enhance the therapeutic benefits of drugs. TheStreet Ratings rates XenoPort as sell. The company's weaknesses can be seen in multiple areas, such as its disappointing return on equity, weak operating cash flow and generally disappointing historical performance in the stock itself. You can view the full XenoPort 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.