The U.S. Treasury conducts auctions to sell new government securities on a regular schedule. Bills (maturities up to 1 year) are sold weekly, notes (2-10 years) and bonds (20-30 years) are sold monthly. The auction process determines the yield at which the government borrows.
Treasury auctions use a single-price, sealed-bid format:
Competitive bidders (primary dealers, institutions, funds) submit bids specifying the yield they require
Non-competitive bidders (retail investors, small institutions) accept whatever yield the auction produces
Awards are filled from the lowest yield bid upward until the offering amount is reached
All winners pay the same price (the highest accepted yield)
Four key metrics gauge auction demand:
Bid-to-cover ratio: total bids divided by the amount sold. Higher means stronger demand.
Tail: the difference between the auction high yield and the pre-auction when-issued yield. A small or negative tail indicates strong demand.
Indirect bidders: share awarded to foreign central banks and institutions (bidding through primary dealers). Higher indirect participation signals strong international demand.
Direct bidders: share awarded to institutions bidding directly with Treasury.
Auction results move markets. A weak auction (large tail, low bid-to-cover) can push yields higher across the curve, while a strong auction can compress yields. The auctions tool on this site grades each auction from D- to A based on normalized historical performance across all four metrics.