The most recent addition to the list of primary dealers was Wells Fargo Securities LLC on April 18, 2016. The last previous addition was TD Securities (USA) LLC on February 11, 2014. Name changes of the firms are fairly common as are withdrawals due to mergers; for example, when Merrill Lynch was taken over by Bank of America, the Merrill Lynch name was at first withdrawn but the Bank of America dealer firm was later renamed Merrill Lynch.[9]
The process begins several days before the scheduled auction when the Treasury announces the details of the upcoming issue, including the amount to be auctioned and the maturity date. When you participate in an auction, you have two bidding options – competitive and noncompetitive. TreasuryDirect allows noncompetitive bidding only. Noncompetitive bidding is limited to purchases of $5 million per auction. Bidding limits apply cumulatively to all methods (TreasuryDirect, banks, and brokers) that are used for bidding in a single auction.
The bill auction accepts competitive bids to determine the discount rate to be paid on each issue. A group of securities dealers, known as primary dealers, are authorized and obligated to submit competitive bids on a pro-rata share of every Treasury bill auction. The winning bid on each issue will determine the interest rate that is paid on that issue. Once an issue is purchased, the dealers are allowed to hold, sell, or trade the bills. The demand for bills at auction is determined by market and economic conditions.
A ring can also be used to increase the price of an auction lot, in which the owner of the object being auctioned may increase competition by taking part in the bidding him or herself, but drop out of the bidding just before the final bid. In Britain and many other countries, rings and other forms of bidding on one's own object are illegal. This form of a ring was used as a central plot device in an episode of the British television series Lovejoy (series 4, episode 3), in which the price of a watercolour by the (fictional) Jessie Webb is inflated so that others by the same artist could be sold for more than their purchase price. 

PLEASE READ THESE TERMS OF SALE CAREFULLY, AS THEY HAVE BEEN RECENTLY UPDATED.  THIS IS AN INTERNET-ONLY AUCTION!  AUCTION CLOSING DATE: Friday, March 22nd 12:07 pm Bidding closes on the first item at 11:07 am, then closes at the rate discussed in these Terms and Conditions of Sale.  INSPECT: Friday, March 15th 9am to 2pm  INSPECT:   [ View Full Listing ]
Whenever bidders at an auction are aware of the identity of the other bidders there is a risk that they will form a "ring" or "pool" and thus manipulate the auction result, a practice known as collusion. By agreeing to bid only against outsiders, never against members of the "ring", competition becomes weaker, which may dramatically affect the final price level. After the end of the official auction an unofficial auction may take place among the "ring" members. The difference in price between the two auctions could then be split among the members. This form of a ring was used as a central plot device in the opening episode of the 1979 British television series The House of Caradus, 'For Love or Money', uncovered by Helena Caradus on her return from Paris.