The special government securities come in two types: short-term certificates of indebtedness, which mature on the following June 30, and bonds with a term of one to 15 years. The short-term certificates and bonds issued to the Social Security trust funds are not traded in the bond market or available to the public. Like other Treasury securities, however, they are backed by the full faith and credit of the U.S. government.
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By the slightest amount of smoke and mirrors, to fool people who are completely economically illiterate.