Jim Simons acquired 1.45 Million Abiomed shares worth $421 Million. That's 0.45% of their equity portfolio (32nd largest holding). The investor owns 3.17% of the outstanding Abiomed stock. The first Abiomed trade was made in Q2 2013. Since then Jim Simons bought shares twenty more times and sold shares on fifteen occasions. The stake costed the investor $297 Million, netting the investor a gain of 42% so far.