offer price: 1. The price at which investors buy new shares or units in a unit trust. The opposite, i.e. the selling price, is called the 'bid price', the difference between the two is the 'spread'. The Bid/Ask Spread and How It Costs Investors Certain large firms, called market makers, can set a bid/ask spread by offering to both buy and sell a given stock.For example, the market maker would quote a bid/ask spread for the stock as $20.40/$20.45, where $20.40 represents the price at which the market maker would buy the stock.