"It's not just whom you sleep with, but also whom they are sleeping with" Warren Buffet on Derivatives contracts which keep various parties entangled for years and can create real hazards once those assets start deteriorating.
In his annual letter to shareholders he admitted making at least one major mistake and several lesser ones calling it "unforced errors", his worst year in four decades. Berkshire Hathaway posted a 62% drop in net income for 2008, and it's shares which peaked in late 2007 at over US$148,000 each closed 27/2/2009 at US$78,600 each.
For the most revered investor in the world, he admitted "did some dumb things". I admired his courage to face up to his mistakes unlike those from Temasek and GIC. Being human, we are sure to make mistakes, most importantly, we have to acknowledge the mistakes and learn from it to avoid repeating the same.