What happened? After more than doubling in value on Thursday, shares of Lexicon Pharmaceuticals (NASDAQ: LXRX) are giving up some of those gains on Friday. The company's stock was down by 13.7% as of 12:39 p.m. EST today, after dropping by as much as 18.6% earlier in the day. The company did not report any news today, but we can probably attribute these losses to two factors. First, it is plausible that some investors are choosing to take some profits after Lexicon's rally yesterday. Second, the stock was downgraded by a Wall Street analyst. So what It isn't every day that shares of a company rise by 105% in a mere 24-hour period, even in the highly volatile biotech industry. But on Thursday, Lexicon reported that it had received positive feedback from the Food and Drug Administration regarding one of its pipeline candidates. The agency thinks the results from two phase 3 clinical trials for Lexicon's sotagliflozin can support a New Drug Application (NDA). The clinical trials in question investigated the cardiovascular efficacy of sotagliflozin in type-2 diabetes patients with worsening heart failure or with other heart-related ailments. Image source: Getty Images. After Thursday's rally, some of the company's investors probably saw an opportunity for a hefty profit. Elsewhere, Gabelli analyst Kevin Kedra downgraded Lexicon's stock to hold from buy. Kedra cited valuation concerns, which makes sense following the company's one-day surge. It is also worth noting that Citigroup analyst Yigal Nochomovitz actually raised his price target for Lexicon to $13, up from $6, and kept a buy rating on the stock. Given that Lexicon's shares closed at $8.05 on Thursday, the analyst thinks there is even more upside left for the healthcare company. Now what What should investors make of all this noise? Not much, in my view. Following yesterday's good news, it is certainly worth keeping an eye on how things develop for Lexicon. But for those willing to pull the trigger now, even after Lexicon's shares more than doubled yesterday, it's important to remember that the company's stock will likely continue to be volatile. 10 stocks we like better than Lexicon PharmaceuticalsWhen investing geniuses David and Tom Gardner have a stock tip, it can pay to listen. After all, the newsletter they have run for over a decade, Motley Fool Stock Advisor, has tripled the market.* David and Tom just revealed what they believe are the ten best stocks for investors to buy right now... and Lexicon Pharmaceuticals wasn't one of them! That's right -- they think these 10 stocks are even better buys. See the 10 stocks *Stock Advisor returns as of November 20, 2020 Prosper Junior Bakiny has no position in any of the stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. The Motley Fool has a disclosure policy.Source