A minimum bid is the minimum required bid for all of your products that belong to a given subcategory to appear in Yahoo Shopping. Some merchants may have a minimum bid that is lower than the default minimum (Default minimums are the published bids that have replaced the rate card). For example, Yahoo Store merchants, who had a 20% discount off the rate card before the launch of the bidded marketplace, will continue to get the same discount since their minimum bids will reflect a 20% discount off the default minimum.
However, advertisers who have a minimum bid below the default receive no advantage in ranking. Their minimum only allows them to have a product appear in Yahoo Shopping at a lower amount. If they actually bid below the default minimum, their lower bid will cause them to rank lower than merchants bidding the default minimum, all other ranking factors being equal.
The minimum bids you see in the Bidding UI or in your Bid feed are your minimum bids for each of your categories. If you do not want to pay more, you can keep your bid at this level. If you want to help improve your traffic in a given category, you may consider increasing your bid. If you bid below your minimum bid in a given category, products in that category will not appear on Yahoo Shopping.
To make bid management simple in the Bidding UI, a red color coded indicator will appear when you have set a bid that is below your minimum in a given category and a green color coded indicator will appear when you have set a bid that is at or above your minimum in a given category.
Please Note: While your bid is only one factor in determining your product placement, a higher bid increases your chance of appearing near the top of the search results in Yahoo Shopping