Typically these bids are sealed - not revealed to the other buyers until the auction closes.
A uniform price auction may be utilised to aggregate a number of units offered by more than one seller to multiple buyers.
This style of auction, sometimes referred to as a call market or double auction, shares the characteristics of an open market mechanism in which all buyers and all sellers interested in trading a homogenous commodity may participate simultaneously.
[3] A variation that preserves the incentive to bid truthfully is the Vickrey-Clark-Groves auction.
To speed up this process, the initial auction price for any subsequent bidding round is set just slightly higher than the previous winning bid (around 15-20 cents, or 15-30% on average).