Treasury bills are issued by the U.S. government with maturities of 1, 3 and 6 months (4-week, 13-week, 26-week bills or 28-day, 91-day, 182-day bills) in order to pay for the national debt and other expenses. The 3- and 6-month Treasury bills are auctioned every Monday and the resulting figures are released to the public the next day. Treasury bill auction results provide the discount rate*, investment yield, and price for recently auctioned bills.

* The discount rate is an annualized rate of return based on the par value of the bills and is calculated on a 360-day basis. The investment yield, or coupon-equivalent yield, is calculated on a 365-day basis and is an annualized rate based on the purchase price of the bills and reflects the actual yield to maturity.

See Also:

• Treasury Bills: Frequently Asked Questions
• Treasury Bills: Historical Graphs
• Constant Maturity Treasury (a.k.a. CMT or TCM): Frequently Asked Questions

Treasury bills can be bought at original issue or on the secondary market. At original issue, the Treasury Department sells new securities to the public. On the secondary market, traders buy and sell previously issued securities.

Following is the definition of the weekly 6-Month T-Bill index (Auction High):

T-Bill indexes have both weekly and monthly values. Monthly values are averages of the past month's weekly T-Bill rates.

The Monthly Treasury Bill (T-Bill) Indexes (Auction High) for a given month are calculated by Mortgage-X using the reported Treasury Bill yields and are usually published on our website on the first Monday of the following month.

The Weekly Treasury Bill (T-Bill) Indexes (Auction High) are usually published on our website on Tuesday for the previous week. The figures reflect week-ending dates (previous Friday).

The monthly 6-Month Treasury Bill index (6-MoT-Bill) is the most often used. ARMs tied to the 6-Month T-Bill usually adjust once every six months.

The Treasury Bill indexes move with the market and respond quickly to economic changes like the CMT indexes. The following graph reflects the movement of the 3-, and 6-Month monthly Treasury Bills and compares them with the monthly 1-Year CMT index.

If you need historical data prior to 1990, please visit the U.S. Treasury website (www.ustreas.gov). Secondary market T-bill rates are contained in the H.15 Federal Reserve Statistical Release.

Note: The index commonly called the 1-Year T-Bill is not a Treasury Bill. It's the 1-Year CMT index. It's important to know the precise name of the index, the names may sound alike, but there is a considerable difference between different indexes. Most 1-Year ARMs are tied to the CMT index.

See Also:

• Treasury Bills: Frequently Asked Questions
• Treasury Bills: Historical Graphs
• Constant Maturity Treasury: Frequently Asked Questions

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