A market is said to be perfectly-competitive when: the market may be dominated by one or two major companies, but there are many smaller companies also in the market. there are any number of products, equivalent buying and selling prices, and individual buyers or sellers can affect those prices by their own actions. there is a homogeneous product, equivalent buying and selling prices, and no individual buyers or sellers can affect those prices by their own actions. there is no opportunity costs incurred by the vendor nor by the buyer. there are any number of products, equivalent buying and selling prices, and individual buyers or sellers can affect those prices by their own actions, but there are no opportunity costs for buyers or sellers