Abstract: This invention provides a compression method of stock price data, capable of greatly reducing a total byte number which is required so as to process stock price data. While an attention is paid to a stock dealing volume and a relationship among a starting value, a high value, a low value, and a closed value, which may occur in the security trading, two sorts of classifications are previously set, and also each of these two classifications is further previously subdivided into a plurality of patterns. Also, classification identification data which pattern of the respective classifications a set of the stock price data belongs to is used.

Abstract: A chart used to show the current price of stocks of a particular brand prevailing at a particular point of time of day, a limit price set by an investor for each selling or buying order not yet executed, and the number of stocks available at each set price is arranged to show those prices along the ordinate axis, and the number of stocks along the abscissa axis, and has a price range portion 10 formed by a segment 4 joining along the ordinate axis a single current price plot 1 representing the current price and one or more limit price plots 2a, 2b, . . . representing the limit price or prices set for a selling or buying order or orders, and a stock number representing portion 20 starting at each limit price plot 2a, 2b, . . . on the price range portion 10 and extending along the abscissa axis in accordance with the number of stocks corresponding to each limit price.