NEW YORK ( TheStreet) -- Shares of XenoPort (Nasdaq: XNPT) were gapping down Monday morning with an open price 13% lower than Friday's closing price. The stock closed at $6.67 Friday and opened today's trading at $5.80. The average volume for XenoPort has been 535,400 shares per day over the past 30 days. XenoPort has a market cap of $243.7 million and is part of the health care sector and drugs industry. Shares are down 21.7% year to date as of the close of trading on Friday. 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 and generally disappointing historical performance in the stock itself. You can view the full XenoPort Ratings Report. Get more investment ideas from our investment research center. Interested in other stocks that are gapping down? Get free SMS text alerts sent to you when the action happens by texting DOWN to 95370 or select from multiple alert options.