Ken Griffin acquired 7.58 Million MerckInc shares worth $998 Million. That's 1.01% of their equity portfolio (8th largest holding). The first MerckInc trade was made in Q2 2013. Since then Ken Griffin bought shares 52 more times and sold shares on 50 occasions. The stake costed the investor $592 Million, netting the investor a gain of 69% so far.