By Vicki Needham - 08/11/10 10:11 PM EDT
The first purchase of debt is expected Aug. 17 and, after nine buying operations, will end Sept. 13. The Fed is expected to announce its next round of buying in mid-September.
Some in the financial markets questioned whether the debt-buying plan would be enough to provide the needed economic boost.
U.S. stock markets plunged 2.49 percent today on more bad economic news, including an expansion of the trade gap, with exports dropping off and imports rising.