<P> The U.S. Federal government suspended issuing 30 - year Treasury bonds for four years from February 18, 2002 to February 9, 2006 . As the U.S. government used budget surpluses to pay down Federal debt in the late 1990s, the 10 - year Treasury note began to replace the 30 - year Treasury bond as the general, most - followed metric of the U.S. bond market . However, because of demand from pension funds and large, long - term institutional investors, along with a need to diversify the Treasury's liabilities--and also because the flatter yield curve meant that the opportunity cost of selling long - dated debt had dropped--the 30 - year Treasury bond was re-introduced in February 2006 and is now issued quarterly . </P> <P> Treasury Inflation - Protected Securities (or TIPS) are the inflation - indexed bonds issued by the U.S. Treasury . The principal is adjusted to the Consumer Price Index (CPI), the commonly used measure of inflation . When the CPI rises, the principal adjusts upward . If the index falls, the principal adjusts downwards . The coupon rate is constant, but generates a different amount of interest when multiplied by the inflation - adjusted principal, thus protecting the holder against the official inflation rate (as asserted by the CPI). TIPS were introduced in 1997 . TIPS are currently offered in 5 - year, 10 - year and 30 - year maturities . </P> <P> Separate Trading of Registered Interest and Principal Securities (or STRIPS) are T - Notes, T - Bonds and TIPS whose interest and principal portions of the security have been separated, or "stripped"; these may then be sold separately (in units of $100 face value) in the secondary market . The name derives from the days before computerization, when paper bonds were physically traded; traders would literally tear the interest coupons off of paper securities for separate resale . </P> <P> The government does not directly issue STRIPS; they are formed by investment banks or brokerage firms, but the government does register STRIPS in its book - entry system . They cannot be bought through TreasuryDirect, but only through a broker . </P>

The public debt is held as treasury bills treasury notes treasury bonds and u.s. savings bonds