BOSTON ( TheStreet) -- Hedge funds and other large institutional investors peeled back the curtain this week to reveal a bit about what biotech stocks they were buying and selling during the third quarter. Funds that manage more than $100 million are required to disclose their equity holdings, options and convertible debt on a Form 13F filed with the Securities and Exchange Commission within 45 days of the end of a quarter. Funds aren't required to report short positions betting on declines. Since these disclosures are lagging, it's also not possible to tell what hedge funds have done with these biotech stocks since Sept. 30 when the third quarter ended. Still, combing through 13F filings can give individual investors some inkling into where professional investors are placing their biotech investment capital. On the following pages, you'll find a snapshot of 10 biotech stocks with significant institutional investor buying and selling during the third quarter.