Repos are used by Wall Street prime brokers to borrow huge sums of money to finance bond inventories and make deliveries on short positions. It is the largest market in the world, but largely unknown outside of the world of fixed-income cognoscenti. Repos are also the vehicle hedge funds and other proprietary trading accounts use to leverage up cash to finance derivatives positions -- and leverage was arguably the biggest factor behind the Wall Street 2008 meltdown. This book lays out the basic structure of repos, the hows and whys of them. It also describes "the carry game" and details the numerous defaults involving repos that led to major changes in the structure and legalities surrounding them, as well as offering a brief overview of the evolution of the MBS market since the 1990s. Let the borrower beware! .... But also let them get their hands on this essential primer about this enormous and extremely influential market. The author Ellen Taylor headed up repo desks for two primary bond dealers before becoming a financial writer and editor covering repos and bonds for Bloomberg News, Barrons, Knight Ridder Financial, Global Custodian, and Market News. Contact etaylorrepo@gmail.com for information about how to access this book.