The Product-Mix Auction is a new way to sell or buy different types of goods at once. Bidders can offer different prices for each type of item, and the auction picks the best offer for each bidder. This auction is more efficient and fairer than other methods, like separate auctions for each type of item. It's also faster and less likely to be influenced by collusion. The Bank of England uses this auction to loan funds secured against different types of collateral, especially during times of financial stress. The auction was praised for its practical application in financial markets.