Besides the sellers' cartel just described, buyers may also form cartels to suppress the price of a purchased input. Another type of cartel is the bidding ring. In bid rigging potential suppliers form an agreement as to which of them will win a supply contract at a price above the competitive price and, if one of them wins, then agree to a rule for sharing the extra profits among themselves. Bid rigging is most common among construction firms trying to get a government building project. 