What Is a Bill Auction?

What Is a Bill Auction?

4 Min.

Every week, the government conducts an electronic bill auction to issue Treasury bills to the public. Institutional and individual investors are welcome to participate, as well as 24 primary dealers consisting of financial institutions and brokerages who are required to take part. Participants are divided into two groups: competitive and non-competitive bidders. Competitive bids determine the discount rate that will be paid on each T-bill issue. Non-competitive bidders are guaranteed to receive their securities, although they must accept the rate set by the competitive bidders. The lowest discount rate that meets the supply of debt being sold is considered the "winning" yield.


In the United States, the U.S. Treasury conducts weekly public auctions to issue federal debt obligations. These obligations primarily consist of Treasury bills (T-bills) with maturities spanning from one month to one year. The auction process involves 24 authorized primary dealers mandated to actively participate in bidding for each issue. This framework serves as the official method for the issuance of all U.S. Treasury bills.

Exploring a Bill Auction

The weekly bill auction employs an electronic Dutch auction model, wherein investors submit bids indicating the quantity and price of the desired securities. Unlike traditional auctions, where bids incrementally escalate, the final price is established after aggregating and sorting all bids.

The initiation of this process is heralded by an announcement released days before the scheduled auction. This notice encompasses crucial details such as the auction date, issue date, quantity of securities for sale, bidding deadlines, and eligibility criteria. Bidders can submit their bids up to 30 days before the auction commences.

As the auction unfolds, competitive bids are welcomed to ascertain the discount rate applicable to each issue. A designated group of primary dealers, comprising banks and brokerages, is both authorized and compelled to present competitive bids, proportionally contributing to each Treasury bill auction.

The winning bid for each issue establishes the corresponding interest rate. After the acquisition of bills, dealers possess the freedom to hold, sell, or trade them, with market and economic conditions dictating the demand for Treasury bills at auction.

Diverse Participants in Treasury Auctions

Treasury auctions draw a diverse group of participants, encompassing both retail and institutional investors. Bidders fall into two categories: competitive and non-competitive tenders. Smaller investors typically submit non-competitive tenders, committing to accept the final discount rate determined by the competitive side of the auction, even though the exact price remains unknown until the auction concludes.

In contrast, larger institutional investors engage in competitive tenders, with each bidder limited to 35% of the offering amount per bill auction. Competitive bids specify the investor's minimum acceptable rate or discount margin for the debt securities. The bids with the lowest discount rates are prioritized, determining the "winning" yield, or the highest accepted yield, after deducting non-competitive bids from the total securities offered.

Unlike non-competitive bidders, those submitting competitive tenders are not assured of receiving T-bills; their bid approval depends on the discount yield they proposed. Investors bidding at or above the winning yield level, whether competitive or non-competitive, secure securities at the established discount rate. The non-competitive bid closing time for bills is typically 11:00 a.m. Eastern Time on the auction day, while the competitive bid closing time is 11:30 a.m. Eastern Time.

How Does a Bid Auction Work?

Illustrating the operation of a bid auction, consider a scenario where the Treasury aims to raise $9 million through one-year T-bills with a 5% discount rate. (Bills are purchasable in increments of $100, with par values typically ranging from $1,000 to $10,000.) Competitive bids are submitted as follows:

  • $1 million at 4.79%
  • $2.5 million at 4.85%
  • $2 million at 4.96%
  • $1.5 million at 5%
  • $3 million at 5.07%
  • $1 million at 5.1%
  • $5 million at 5.5%

To optimize yield, the Treasury accepts bids with the lowest discount rates first. With a target of $9 million, bids with rates up to 5.07% are accepted. However, of the $3 million bid at 5.07%, only $2 million is approved. Bids below 5.07% are accepted, while those above are rejected. Consequently, the auction concludes at a 5.07% discount rate, applicable to all successful bidders.

On the issuance day, the Treasury delivers T-bills to non-competitive bidders from the specific auction, charging their accounts for the securities. The T-bill's purchase price is denoted as a per-hundred-dollar figure.


The U.S. Treasury's weekly bill auctions play a pivotal role in issuing Treasury bills to a diverse array of participants, ranging from institutional investors to individual bidders. With 24 authorized primary dealers mandated to participate, the auction process efficiently determines the discount rates paid on each T-bill issue. The distinction between competitive and non-competitive bidders ensures a dynamic auction environment. The final winning yield, established based on the lowest discount rates meeting the debt supply, marks the culmination of each auction, shaping the landscape for subsequent T-bill transactions.

Bill Auction
Treasury Bill
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