George Soros acquired 2.23M Interactive Brokers Group shares worth $144M. It makes up 4.96% of their stock portfolio and is their biggest holding. The first Interactive Brokers Group trade was made in Q3 2011. Since then George Soros bought shares nine more times and sold shares on four occasions. The stake costed the investor $80.8M, netting the investor a gain of 78% so far.