Treasury bills (T-bills) are obligations of the United States government, generally issued with 4-, 13-, 26-, and 52-week maturity periods. Treasury bills are issued in minimum denominations of $100 with $100 increments thereafter. Treasury bills are issued without interest and on a discount basis (that is, they are issued at a price that is less than the amount for which they will be redeemed at maturity). The price is determined at auction (13- and 26-week bills are generally auctioned on Monday of each week; four-week bills are generally auctioned on Tuesday of each week; 52-week bills are generally auctioned every four weeks on Tuesday).