Credit default swaps opened up important new avenues to speculators. Investors could go long on a bond without any upfront cost of buying a bond; all the investor need do was promise to pay in the event of default. Shorting a bond faced difficult practical problems, such that shorting was often not feasible; CDS made shorting credit possible and popular. Because the speculator in either case does not own the bond, its position is said to be a synthetic long or short position.