It was a year of amazing highs and humiliating lows for biotech companies. The industry gained steam early in the year, sending the NASDAQ Biotechnology Index to an all-time high. But, the proverbial pats on the back didn’t last long. A drug-pricing scandal led by Turing Pharmaceuticals, a federal investigation into Valeant Pharmaceutical’s (VRX) business practices, and questions about the efficacy of blood-testing technology at Theranos’ drove a sell off in the sector that sent the index plummeting 27% by the end of September from its peak. The biotech index spent the rest of the year slowly climbing back from the loss, eking out a slight gain in the end.

This article is part of Fortune’s Best in Business 2015 package of highlights and lowlights of the year in business, politics and the economy by the writers and editors of Fortune. To see the entire package, click here.