PRIMECAP Management acquired 6.76M AMGEN shares worth $2.72B. That's 1.63% of their equity portfolio (13th largest holding). The investor owns 1.25% of the outstanding AMGEN stock. The first AMGEN trade was made in Q1 2013. Since then PRIMECAP Management bought shares five more times and sold shares on 48 occasions. The stake costed the investor $607M, netting the investor a gain of 348% so far.