Prem Watsa acquired 2.4M Marsh & McLennan Cos. shares worth $495M. That's 24.30% 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 853k shares. The stake costed the investor $75.5M, netting the investor a gain of 556% so far.