For years, the product that Ms. Masters and her colleagues invented remained just a mechanism for offloading risk in high-grade corporate lending. But as often occurs with Wall Street alchemy, a good idea started to be misused — and a product initially devised to insulate against risk soon morphed into a device that actually concentrated dangers.
This shift began in 2002, when low interest rates pushed investors to seek higher returns.
via The Reckoning – How Merrill Lynch Faltered and Fell – Series – NYTimes.com