An amount of interest to buy a stock in a stock market is determined based on a plurality of messages in which each of a plurality of brokers or dealers specifies an interest to buy the stock, a respective size of the stock to buy, and a respective price to buy the stock. The amount of interest to buy the stock in the stock market is visually represented in a user interface by a region approximately shaped as a circular annulus sector whose outer radius is based on the amount of interest to buy the stock. The outer radius is independent of a price change of the stock.