Each year, billions of dollars are invested in the private equity and private real estate markets; in 2013 alone, $454 billion of new equity was reportedly raised globally.  All of these investments are not only private, but also highly illiquid.  Unlike their hedge fund counterparts, private equity funds typically do not allow investors an early out should their investment circumstances change.  To provide some measure of liquidity to an otherwise illiquid asset class, an active secondary market has arisen in the private marketplace.  There are several reasons why a secondary market transaction might be attractive to a seller.  Given the illiquid nature of these interests, however, each sale must be privately negotiated, raising legal and deal issues for both seller and buyer.  In a guest article, Tyler Hilton and Gary J. Cohen, associate and partner, respectively, at Sidley Austin LLP, offer a comprehensive catalogue of these issues, and discuss best practices for handling them.