Joel Greenblatt, the founder of the $6.8 billion Gotham Asset Management fund, has signaled a cautious sentiment towards two-mega cap pharma stocks. In the third quarter, Greenblatt slashed the fund’s holding of both Valeant Pharmaceuticals Intl Inc (NYSE:VRX) and Gilead Sciences, Inc. (NASDAQ:GILD). His moves are closely followed by traders all over the world, keen for an insight into how one…