The famous hedge fund manager, author of fantastic books such as Fooling Some of the People All of the Time and founder of Greenlight Capital, David Einhorn made headlines with a presentation at Jim Grant's spring investor conference today. It's funny to say this because AerCap's stock more than doubled since the announcement, but I don't think that Mr. Market full appreciates how cheaply the company purchased AIG's airplane leasing business for and how much it will benefit it. Courtesy of the excellent Reminiscences of a Stock Blogger blog, AER received a $6 billion discount to fair value for the new business, which will help fill out its order book with a ton of near-term deliveries, is accretive to earnings and should enable it to make money on the discounted planes that it purchased that are scheduled to come off-lease in the near future. Add to that the fact that it should be able to refinance much of the ILFC debt at cheaper rates to save even more money down the road. And the fact that the tax inversion the company experiences as one that has its headquarters in Ireland rather than the U.S. will save it even more money. If the company doesn't mess up the integration of its new portfolio 50% to 75% upside in the stock is very possible.