What: Orexigen Therapeutics (NASDAQ:OREX) ended the day down 8.6% after Wells Fargo downgraded its recommendation from an outperform rating to a market perform rating.

So what: In January, Orexigen was listed as one of Wells Fargo's top biotech picks for 2015. Oh, what a year brings.

Orexigen's obesity drug Contrave was launched a little over a year ago with a bang. It worked better than Arena Pharmaceuticals' (NASDAQ:ARNA) Belviq and had a better safety profile than VIVUS' (NASDAQ:VVUS) Qsymia. And it was the only one of the three that could claim it wasn't causing cardiovascular problems.

Unfortunately, Orexigen Therapeutics is finishing the year with a whimper. Sales have followed the same fate as Arena Pharmaceuticals and VIVUS. To get people on the drug, Orexigen's marketing partner Takeda Pharmaceuticals has had to offer discounts and free product, cutting into Orexigen's royalties.

Orexigen looked like it was in a better position than Arena Pharmaceuticals and VIVUS in the EU because it was the only one that had gained marketing approval there. Management had previously indicated they were looking for a partner outside the U.S., but recently conceded that Orexigen will retain marketing rights and partner with local experts for promotion and distribution. While the drug will eventually get launched in Europe, it's a substantial delay -- into the second half of next year -- and won't come with the backing that a major pharmaceutical company could have offered.

Now what: A downgrade from Wells Fargo doesn't make Orexigen Therapeutics less valuable, but it may be what's caused some investors to throw in the towel. Orexigen is cheap, weighing in at a market cap under $300 million, but it's hard to see a quick turnaround from here.