Prem Watsa acquired 2.4 Million Marsh & McLennan Cos. shares worth $520 Million. That's 28.40% of their entire equity portfolio (2nd largest holding). Prem Watsa started to build up the position in Marsh & McLennan Cos. in Q2 2007. Since then they sold 853 Thousand shares. The stake costed the investor $75.5 Million, netting the investor a gain of 589% so far.