Ken Griffin acquired 1.47 Million Costco Wholesale shares worth $714 Million. It makes up 1.06% of their stock portfolio and is their biggest holding. The first Costco Wholesale trade was made in Q2 2013. Since then Ken Griffin bought shares 47 more times and sold shares on 31 occasions. The stake costed the investor $420 Million, netting the investor a gain of 70% so far.