Ken Griffin acquired 1.95 Million Merck & Co shares worth $181 Million. That's 0.27% of their equity portfolio (50th largest holding). The first Merck & Co trade was made in Q2 2013. Since then Ken Griffin bought shares 42 more times and sold shares on 36 occasions. The stake costed the investor $139 Million, netting the investor a gain of 31% so far.