Glenn Greenberg acquired 9.88 Million American Express shares worth $2.8 Billion. It makes up 66.86% of their stock portfolio and is their biggest holding. The investor owns 1.44% of the outstanding American Express stock. Glenn Greenberg started to build up the position in American Express in Q1 1999 and continued to invest until Q1 2009. Since then they sold 1.45 Million shares. The stake costed the investor $244 Million, netting the investor a gain of 1050% so far.