Description

SYSTEM AND METHOD FOR AUTOMATIC STOCK TRADING, AND RECORDING MEDIUM RECORDED WITH A PROGRAM

THEREFOR.

Technical Field

[1] The present invention relates to a method and system for trading spot stocks or stock price index futures through a data communication network, and more particularly, to a method and system for automatically placing an order based on trading conditions input by an investor and market situations analyzed by a computer. Background Art

[2] In a conventional method and system for trading stocks through a data communication network, an inventor input offered trading price and amount of a specific stock and other trading conditions in a computer. According to the input trading conditions, a trading order is placed. After that, the trading may be contracted.

[3] Now, a conventional stock trading method through a data communication network will be described with reference to FIG. 1. An investor allows a computer system 10 to access a stock exchange system 30 through a data communication network 50 so as to check a balance of an account, his own stocks, current prices of own stocks, yesterday ending prices, or the like.

[4] After the investor checks his own account and market situations, the investor places a trading order of a specific stock. The order is transmitted to the stock exchange system 30. The stock exchange system 30 receives trading orders from security companies through the data communication network 50. The stock exchange system 30 contracts the trading at a specific price based on offered selling prices and amounts of stocks and offered buying prices and amounts of stocks.

[5] The inventors needs to analyze the market situations and considers the analyzed market situations before inputting the trading conditions. However, high-level professional knowledge and long time are required for analysis of the market situations and generation and input of new trading conditions. Therefore, it is difficult for individual investors to suitably adapt to a change of the stock market and determine trading conditions.

[6] In addition to the individual investors, security companies or experts also spend a lot of personnel and time so as to analyze and adapt the market situations. However, the security companies or experts cannot always select optimal trading timing due to personal difference in time of responding the market.

[7] In order to solve the above problem, Korean Patent No. 2000-62553 (Publication

Date: June 16, 2001) discloses an automatic trading order method and system for repetitively generating an trading order as a substitute for an investor including an individual inventor or an institutional investor.

[8] According to the above Patent Document, the automatic trading order method includes a step of inputting desired trading conditions; a step of placing a selling or buying order according to the desired trading conditions through a data communication network, a step of checking conclusion of the trading through the data communication network, and a step of, if the selling or buying order is concluded, placing a new selling or buying order according to predetermined trading conditions in the computer.

[9] That is, if the selling or buying order is concluded, the computer is allowed to place a new trading order, so that it is possible to reduce investor's burdens to checking the conclusion of the trading and inputting new trading conditions. Here, the new trading conditions denote trading conditions that the investor has input in the computer system in advance under the assumption that the initial trading is concluded.

[10] For example, the initial trading conditions may be buying of 100 stocks of "A" company with 1,000 wons per a stock, and the new trading conditions may be selling of 100 stocks of "A" company with 1,200 wons per a stock. If the buying is concluded according to the initial trading conditions, the investor holds 100 stocks of "A" company with 100,000 wons. Next, if the selling is automatically concluded through the computer according to the new trading conditions input by the investor in advance, the investor earns 20,000 wons.

[11] However, such an automatic stock trading method is effective in a case where a trend of the stock market can be predicted and the trading conditions suitable for the trend are input. However, the method cannot cope with an unexpected change of the market, so that loss cannot be prevented.

[12] In addition, the conventional automatic stock trading method is not optimized with respect to various investment methods. Therefore, when an investor uses various trading methods, the conventional automatic stock trading method cannot be effectively used. Disclosure of Invention Technical Problem

[13] The present invention provides an automatic stock trading method and system capable of automatically monitoring and analyzing a change of a market and determining trading in consideration of trading conditions input by an investor and market situations and a storage medium storing an automatic stock trading program.

[14] The present invention also provides an automatic stock trading method and system capable of allowing an investor to select a trading method such as an arbitrage trading

method, a pair trading method, a volatility trading method, and a stock- futures/spot-stock composite trading method and determining optimized trading in consideration of market situations according to the trading method and a storage medium storing an automatic stock trading program. Technical Solution

[15] According to an aspect of the present invention, there is provided an automatic stock trading method for trading spot stocks and stock price index futures by using a computer system connected to a data communication network, comprising: a trading method selecting step of selecting one of trading methods including an arbitrage trading method, a pair trading method, a volatility trading method, and a stock- futures/spot-stock composite trading method in the computer system; a trading condition input step of inputting trading conditions such as accounts, companies, trading amounts, and trading prices required for the trading method selected in the trading method selecting step; a market-situation checking/analyzing step of checking market situations such as current prices, traded amounts, basis ratios, and average moving lines associated with the trading of the trading method and comparing and analyzing the trading conditions input in the trading condition input step in the computer system; a trading determining step of determining trading based on the trading conditions input in the trading condition input step and the market situations analyzed in the market-situation checking/analyzing step in the computer system; and a placing/contracting checking step of automatically placing a selling or buying order according to the determination of the trading determining step and checking contracting through the data communication network in the computer system.

[16] In the above aspect of the present invention, the trading method selected in the trading method selecting step may be the arbitrage trading method, wherein the trading conditions input in the trading condition input step include basis-ratio-section-based selling and buying positions, wherein the market-situation checking/analyzing step includes a step of calculating a market basis ratio of the to-be-invested companies, and wherein the trading determining step includes a step of determining trading according to the market basis ratio calculated in the market-situation checking/analyzing step and holding positions in basis ratio sections input in the trading condition input step.

[17] In addition, the trading method selected in the trading method selecting step may be the pair trading method, wherein the trading conditions input in the trading condition input step include a pair of companies having high correlation, wherein the market- situation checking/analyzing step includes a step of calculating increase rates of the companies in the pair, and wherein the trading determining step includes a step of determining selling the company having a relatively high increase rate by a relative

strength and buying the companying having a relatively low increase rate by a relative strength.

[18] In addition, the trading method selected in the trading method selecting step may be the pair trading method, wherein three or more companies constitute one pair group.

[19] In addition, the trading method selected in the trading method selecting step may be the volatility trading method, wherein the trading conditions input in the trading condition input step include to-be-traded companies, a total investment amount, investment ratios of the companies to the total investment amount, and adjusting ratios of the companies, wherein the market- situation checking/analyzing step includes a step of checking current prices of the companies and analyzing a change in the market ratios, and wherein the trading determining step includes a step of adjusting the investment ratios by products of the differences between the market ratios and the investment ratios with the adjusting ratios and determining selling or buying according the adjusted investment ratios.

[20] In addition, the trading method selected in the trading method selecting step may be the stock-futures/spot-stock composite trading method, wherein the trading conditions input in the trading condition input step include basis-ratio-section-based selling and buying positions, companies included in a spot stock balance at the time of the arbitrage trading, and the spot stock trading method, wherein the market-situation checking/analyzing step includes a step of calculating a market basis ratio and checking market situations required for the input spot stock trading method, and wherein the trading determining step includes a step of determining arbitrage trading according to the market basis ratio calculated in the market- situation checking/ analyzing step and the selling and buying positions in the basis ratio sections input in the trading condition input step and determining trading according to the spot stock trading method selected for the companies included in the spot stock balance at the time of the arbitrage trading and the market situations.

[21] In addition, the trading method selected in the trading method selecting step may be the stock-futures/spot-stock composite trading method, wherein the trading conditions input in the trading condition input step include basis-ratio-section-based selling and buying position and a pair of companies having a high correlation at the time of the arbitrage trading included in the spot stock balance, wherein the market- situation checking/analyzing step includes a step of calculating a market basis ratio and relative increase rates of the companies in the pair included in the spot stock balance at the time of the arbitrage trading, and wherein the trading determining step includes a step of determining arbitrage trading according to the market basis ratio calculated in the market- situation checking/analyzing step and the selling and buying positions in the basis ratio sections input in the trading condition input step and determining selling the

company having a relatively high increase rate by a relative strength among the companies in the pair included in the spot stock balance at the time of the arbitrage trading and buying the company having a relatively high increase rate by a relative strength.

[22] In addition, wherein the trading conditions input in the trading condition input step include basis-ratio-section-based selling and buying positions, companies for spot stock trading included in a spot stock balance at the time of the arbitrage trading, the volatility trading method as the spot stock trading method, a total investment amount for the spot stock trading, investment ratios of the companies for the spot stock trading to the total investment amount, and adjusting ratios, and wherein the market- situation checking/analyzing step includes a step of calculating a basis ratio, checking current prices of the companies, and analyzing a change in the market ratios, and wherein the trading determining step includes a step of determining trading according to the market basis ratio calculated in the market-situation checking/analyzing step and the selling and buying positions in the basis ratio sections input in the trading condition input step, adjusting the investment ratios by products of the differences between the market ratios of the companies for the spot stock trading included in the spot stock balance at the time of the arbitrage trading with the adjusting ratios and determining trading of the spot stocks according to the adjusted investment ratios. Brief Description of the Drawings

[23] FIG. 1 is a block diagram for explaining a conventional stock trading method using a data communication network.

[24] FIG. 2 is a block diagram showing an automatic stock trading system according to the present invention. Best Mode for Carrying Out the Invention

[25] Hereinafter, embodiments of the present invention will be described in detail with reference to FIG. 2. FIG. 2 is a block diagram showing an automatic stock trading system according to an embodiment of the present invention.

[26] The automatic stock trading system according to a first embodiment of the present invention includes a trading method selecting module 22, a trading condition input module 24, a market- situation checking/analyzing module 26, a trading determining module 28, and a placing/contracting checking module 29.

[27] Firstly, an investor selects a trading method among arbitrage trading, pair trading, volatility trading, and stock-futures/spot-stock composite trading through the trading method selecting module 22 and inputs trading conditions required for the selected trading method through the trading condition input module 24. Basic trading conditions includes an account used for trading, companies, desired trading prices,

desired trading amount, and the like.

[28] The market-situation checking/analyzing module 26 accesses a stock exchange system 30 through a data communication network 50 to check market situations including a current price, a trading amount, average moving lines, a stock price index, a basis ratio, and the like. A database accessed by the market- situation checking/ analyzing module 26 through the data communication network 30 is not limited to the stock exchange system of a stock exchange market, but any database capable of checking the market situations can be accessed.

[29] The trading determining module 28 receives the trading method, the trading condition, and the market situations through the trading method selecting module 22, the trading condition input module 24, and the market- situation checking/analyzing module 26, respectively, and collectively determines trading.

[30] The placing/contracting checking module 29 accesses the stock exchange system 30 through the data communication network 50 to place an order and check contracting of the trading according to the trading conditions received from the trading determining module 28.

[31] Unlike the conventional automatic stock trading system where the trading is contracted under the trading conditions one-sidedly set by an investor, in the automatic stock trading system according to the first embodiment of the present invention, the computer checks and analyzes the market situations and determines trading in consideration of the analyzed market situations and the trading conditions set by the investor, so that a market-adaptable automatic stock trading can be performed so as to be actively and rapidly adapted to the market situations.

[32] In addition, in the automatic stock trading system according to the first embodiment, since the investor can select the trading method, various investment techniques can be satisfactorily employed.

[33] In addition, since profession analysis of market situations corresponding to the various investment techniques and applications thereof are automatically performed, more professionalized stock investment environments can be provided to general persons.

[34] In addition, since the profession analysis of market situations corresponding to the various investment techniques and applications thereof are performed in real time by the computer, it is possible to minimize loss caused from overlooking of a change in the market situations and missing of optimal trade timing.

[35] Now, an automatic stock trading system using arbitrage trading as a trading method according to a second embodiment of the present invention will be described with reference to FIG. 2.

[36] In the embodiment, trading conditions that can be input in the trading condition input

module 24 includes basis-ratio-section-based selling and buying positions. The market- situation checking/analyzing module 26 calculates a market basis ratio. The trading determining module 28 determines trading according to the market basis ratio calculated by the market- situation checking/analyzing module and the basis-ratio-section-based selling and buying positions input in the trading condition input module.

[37] The arbitrage trading is sometimes refereed to as an arbitrage trading. The arbitrage trading is a riskless profit transaction using a discrepancy between a stock- futures price and a spot stock price in a stock price index futures market.

[38] In the arbitrage trading, if there is a temporary discrepancy between a real price of the stock price index futures and an theoretical price which is a spot stock price added with a financial fee in the stock price index futures market, a relatively high price one is sold, and a relatively low price one is bought, so that a reckless profit corresponding to a reduction of the discrepancy can be obtained in the future that the two prices are recovered to normal prices.

[39] For example, if the real price of the stock price index futures is higher than the theoretical price, the stock-futures price is evaluated to be relatively high. Therefore, a buying arbitrage trading of selling the stock price index futures and buying the spot stock is performed.

[40] On the contrary, if the real price of the stock price index futures is lower than the spot stock price, the real price of the stock price index futures is evaluated to be relatively low. Therefore, a selling arbitrage trading of buying the stock price index futures and selling the spot stock is performed.

[41] A basis denotes a discrepancy between the stock- futures price and the spot stock price in the stock market, that is, (basis) = (stock-futures price)-(spot stock price). If the basis is positive, the market is called "in contango." If the basis is negative, the market is called "in backwardation."

[42] For example, in the second embodiment of the present invention, if the basis ratio is -

0.1% or less (the backwardation occurs), the investor may clear all the funds; if the basis ratio is in a range of -0.1% to 0.5%, the investor may enter only 30% of the fund; if the basis ratio is in a range of 0.5% to 1.1%, the investor may enter 60% of the fund; and if the basis ratio is 1.1% or more, the investor may enter 90% of the fund. In this case, the investor inputs and sets basis-ratio-section-based selling and buying positions (that is, basis-ratio-section-based holding positions) through the trading condition input module 24.

[43] The market-situation checking/analyzing module 26 stores company-based number of shares, initial company-based prices, and KP200 index which are approximate to market ratio at the time of initial fund setting (initial entering) in a database and check whether or not the initial number of shares of each company is maintained.

[44] If the initial number of shares is maintained, the market ratio is maintained. If the market ratio is changed due to a capital increase, a capital decrease, a withdrawal, the number of shares of the company which is approximate to the market ratio is calculated in comparison with yesterday final data (listed number of shares, a flowing stock ratio, and the like) stored in the database, and the database is modified. The initial price of a newly listed company is obtained by multiplying the current price with the initial KP200 price and dividing the result thereof with the current KP200 price, and the database is modified. The results are as follows.

[45] (Number of Shares of Company) = (Investment Amount * (Xi * Pi * Ri ) / sum(Xi *

Pi * Ri )) / Pi

[46] Xi: number of listed shares of each company, Pi: current price of each company, Ri: flowing stock ratio

[47] (Initial Price of Newly Listed Company) = Pi * (Initial KP200 Price)/(Current KP200

Price)

[48] In this manner, the changed data of each company are automatically checked, and the database is updated.

[49] The market-situation checking/analyzing module 26 checks the changed data of each company and calculates the basis ratio of the fund. More specifically, the basis ratio can be calculated by dividing a sum amount of products of the number of shares of the companies and the current prices by a sum amount of products of the number of shares of the companies and the initial prices, dividing the resulting value multiplied with the initial KP200 index with the current stock-futures prices, and subtracting 1 from the resulting value. The calculation is formulized as follows.

[50] (Basis Ratio) = (Stock-Futures Price)/((sum(Xi * Pi)/sum(Xi * Po))*(Initial KP200

Index)- 1)

[51] (Xi: number of shares of each company, Pi: current price of each company, Po: initial price of each company)

[52] The initial price denotes a price at the first investment after establishment of fund.

[53] The trading determining module 28 calculates to-be-entered (held) number of shares of each company based on basis-ratio-section-based selling and buying positions calculated by the market-situation checking/analyzing module 2 and the basis ratio input in the trading condition input module 24.

[54] As described later, if a total entering ratio is determined, the to-be-held number of shares of each company is obtained by multiplying the number of shares corresponding to the investment amount of each company with the entering ratio. The sold amount of stock futures is also obtained by multiplying the total the amount of stock futures corresponding to the total investment amount with the entering ratio.

[55] When the to-be-held number of shares of each company is determined, a previously-

held number of shares is subtracted from the to-be-held number of shares. As a result of the subtraction, if a selling position is needed to be taken, bid price is obtained from the market-situation checking/analyzing module 26. If a buying position is needed to be taken, offered price is obtained from the market- situation checking/analyzing module 26. Next, the basis ratio is calculated.

[56] As a result of the re-calculation, if the basis ratio is larger than a trading discrepancy ratio, trading order is determined and, information of trading order is output to the placing/contracting checking module 29. The placing/contracting checking module 25 accesses the stock exchange system 30 through the data communication network 50 to places the trading order and check contracting of the trading.

[57] For example, firstly, a fund manager determines the market discrepancy ratio based on four variables of the maximum discrepancy ratio, the minimum discrepancy ratio, the trading discrepancy ratio, and the number of sections. If the market discrepancy ratio is equal to or larger than the maximum discrepancy ratio, the manager may the entire fund. If the market discrepancy ratio is smaller than the minimum discrepancy ratio, the manager may clear the entire fund.

[58] If the market discrepancy ratio is larger than the minimum discrepancy ratio and smaller than maximum discrepancy ratio, the manager may sequentially enter (clear) an amount that is obtained by dividing the total fund by the number of sections.

[59] As an example, it is assumed that the maximum discrepancy ratio is 1.0 %, the minimum discrepancy ratio is -0.2%, and the number of sections is 4 days. If the market discrepancy ratio is smaller than -0.2%, 0% of the fund is entered. If the market discrepancy ratio is in a range of -0.2% to 0.2%, 25% of the fund is entered. If the market discrepancy ratio is in a range of 0.2% to 0.6%, 50% of the fund is entered. If the market discrepancy ratio is in a range of 0.6% to 1.0%, 75% of the fund is entered. If the market discrepancy ratio is equal to or larger than 1.0%, 100% of the fund is entered.

[60] In this case, when the trading discrepancy ratio is 0.4%, if the market discrepancy ratio is 0.5%, 50% of the fund is entered. Once the entering of the fund is performed, the system stores the 0.5% as a previous trading discrepancy ratio. If the market discrepancy ratio deviates from the previous trading discrepancy ratio of 0.5% by the trading discrepancy ratio of 0.4%, that is, if the market discrepancy ratio is equal to or smaller than 0.1% if the market discrepancy ratio is equal to or larger than 0.9%, the entering ratios (in this case, 25% and 75%) corresponding to the market discrepancy ratios are calculated. Next, the trading corresponding to the entering ratios is automatically performed.

[61] As a result, 0.5% of the fund is entered, and 0.1% of the fund is cleared. Therefore, an amount obtained by subtracting a trading fee from 0.4% of the fund (that is the net

amount of the entered and the cleared fund) (25%) becomes the established profit.

[62] According to the second embodiment of the present invention, the market- situation checking/analyzing module 26 can calculate the basis ratio immediately in response to a change of the market, and trading is automatically performed based on the basis ratio and the section-based selling and buying positions input through the trading condition input module 24, so that market situation can be automatically recognized by a program without inconvenient determination, and the trading can be performed without loss of chance. Accordingly, it is possible to stably make a profit.

[63] In addition, it is possible to make an additional profit according to a change in basis ratio as well as a conventional arbitrage trading profit.

[64] Now, an automatic stock trading system using pair trading as a trading method according to a third embodiment of the present invention will be described with reference to FIG. 2.

[65] In a conventional generalized pair trading method, two companies that run similar business are selected as a pair, and a fund manager approximately sets a price discrepancy between stock prices of the two companies for swapping stocks. The pair trading method is based on the experience that stocks of the companies running similar business have similar trends of stock prices and the experience that the price discrepancy between stock trends of the two companies in the pair disappears as time e lapses. In the pair trading method, the swapping of stocks is performed according to a relative increase or decrease rate of the companies in the pair.

[66] On the other and, according to a third embodiment of the present invention, a selling or buying stock amount is determined based on a relative strength of an increase rate, so that standardization or formulation of the pair trading can be accomplished. Therefore, according to the third embodiment of the present invention, the pair trading can be more accurately performed, and a profit rate can be checked through quantitatively analysis (comparison of the relative strengths and the profit rates).

[67] According to the third embodiment of the present invention, the market- situation checking/analyzing module 26 calculates the increase rates of the companies in the pair. The trading determining module 28 determines the buying of the company having a high increase rate by the relative strength thereof and the selling of the company having a low increase rate by the relative strength thereof.

[68] As an example, Samsung Electronics (an assumed initial investment of 100 shares) and LG Electronics (an assumed initial investment of 500 shares) are selected as a pair. The stock price of Samsung Electronics is assumed to be increased from 500,000 wons to 600,000 wons, the stock prices of LG Electronics is assumed to be increased from 50,000 wons to 52,000 wons. The increase rate of Samsung Electronics is 20%, and the increase rate of LG Electronics is 4%. Therefore, the stock price of Samsung

Electronics is relatively increased, and the stock price of LG Electronics is relatively decreased. As a result, the buying amounts according to the relative strengths are as follows.

[69] Firstly, initial investment ratios Ri for Samsung Electronics and LG Electronics before change of the stock prices are calculated.

[70] Investment Ratio for Samsung Electronics (Rl) = (500,000 wons * 100 shares)/(500,000 wons * 100 shares + 50,000 wons * 500 shares) = 66.7%

[71] Investment Ratio for LG Electronics (R2) = (50,000 wons * 500 shares)/(500,000 wons * 100 shares + 50,000 wons * 500 shares) = 33.3%

[72] Next, a total evaluated amount (T) after increase of the stock prices is calculated.

[73] (Total Evaluated Amount after Increase of Stock Price) (T) = (600,000 wons * 100 shares + 52,000 wons * 500 share) = 86,000,000 wons

[74] The numbers of stocks of the companies for maintaining the investment ratios after increase of stock prices are calculated.

[75] (Number of shares of Samsung Electronics) = 86,000,000 wons * 66.7 % / 600,000 wons = 96 shares

[76] (Number of shares of LG Electronics) = 86,000,000 wons * 33.3 % / 52,000 wons =

551 shares

[77] Accordingly, by selling 4 shares of Samsung Electronics and buying 51 shares of LG

Electronics, the pair trading can be completed according to the relative strengths of the increase rates of the companies. In this case, the current price (Pi) for Samsung Electronics is 600,000 wons, and the current price (Pi) of LG Electronics is 52,000 wons.

[78] In the above calculation of the pair trading, if the price discrepancy between stock trends of the pair companies is continuously maintained due to external environment or internal situation of the companies, a tracking error is increased. Therefore, in the system according to the present invention, a difference between the investment ratios (= (a market ratio of the company) - (initial investment ratio)) is multiplied with a ratio (generally, 0.1% ~ 3%) set by the fund manager. Every time that the system starts before daily opening of the market, the resulting value is added to the initial investment ratios, so that the tracking error is controlled. Accordingly, even in a market situation having a strongly biased momentum, profit can be stably ensured through the pair trading.

[79] According to a fourth embodiment of the present invention, three or more companies are selected as a pair group. The market- situation checking/analyzing module 26 calculates the increase rates of the companies in the pair. The trading determining module 28 calculates the relative strengths of the increase rates and determines the buying or selling by the relative strengths.

[80] The same calculation as that of the above example is used for the pair trading of the three or more companies. According to the fourth embodiment of the present invention, it is possible to perform the pair trading of the three or more companies, which cannot be easily performed by a person.

[81] Hereinafter, a volatility trading method in the automatic stock trading system according to a fifth embodiment will be described with reference to FIG. 2.

[82] In a volatility trading method, a predetermined investment amount is selected according to an investment ratio of a to-be-traded company, and the selling or buying of the stocks of the company is performed so that the investment amount can always be maintained.

[83] The investment amount is assumed to be 100,000 wons, and the stock price of the company is assumed to be 1,000 wons. 100 shares are assumed to be bought, and the stock price is assumed to be changed to 2,000 wons. In this case, in order to maintain the initial investment amount of 100,000 wons, 50 shores are sold from the held 100 shares, and thus, the remaining shares become 50 shares. The pattern of trading is repetitively performed according to a change in the stock price.

[84] However, according to the repetition of the trading pattern, stocks of a price- increasing company are continuously sold, so that the held shares thereof are decreased. On the contrary, stocks of a price-decreasing company are continuously bought, so that the held shares thereof are increased. As a result, in a strong market, the profit cannot be maximized, and in a weak market, the loss is further increased.

[85] In the fifth embodiment of the present invention, the market- situation checking/ analyzing module 26 calculates volatilities of market ratios of invested companies. The trading determining module 28 determines buying or selling of stocks of the companies by adjusting the investment ratios (investment amounts) by a product of an adjusting ratio to a difference between market ratio and investment ratio of the companies, so that the volatility trading capable of adaptively responding to a volatility of the market ratio can be performed.

[86] For example, 10 companies are selected as to-be-invested companies, and the investment ratio of "A" company among them is selected as 10%. The stock prices of the other 9 companies are assumed not to be changed, and the stock price of the "A" company is assumed to be increased twice. In this case, according to a conventional volatility trading method, 50% of the held shares of the "A" company needs to be sold.

[87] According to the present invention, since the market ratio of the "A" company is changed by about 20% due to the increase in the stock price, the trading determining module 28 subtracts the investment ratio of 10% from the market ratio of 20% of the "A" company to obtain a difference of 10% and multiplies the difference with a predetermined adjusting ratio (for example, 2%) to obtain a value of 0.2%, and adds the

value of 0.2% to the investment ratio of 10%, so that the adjusted investment ratio of 10.2% is obtained. The trading determining module 28 determines the buying or selling of the stocks of the "A" company according to the adjusted investment ratio.

[88] For example, 100 shares of Samsung Electronics are assumed to be initially bought at the stock price of 500,000 wons with the investment ratio of 10%. The stock price of Samsung Electronics is assumed to be increased to 1,000,000 wons, and the stock prices of the other companies are assumed not to be changed. The investment ratio of Samsung Electronics becomes 20% (=10% x (1,000,000/500,000)).

[89] In a volatility trading method without adjustment, 100 shares (= 100 shares x

(1,000,000/500,000-1)) is sold. However, in a volatility trading method using adjustment, the adjustment ratio of, for example, 4% is entered, so that the investment ratio is changed from 10% to 10.4% (= 10%+(20%-10%)*4%). The number of shares is increased by 4 share to be 104 shares (= 100 share x (10.4%/10%)). Accordingly, the to-be-sold shares are adjusted by 4 shares to be changed from 100 shares to 96 shares.

[90] That is, after the adjustment, shares reduced by 4 shares are sold. If the adjustment is continuously performed every time that the market opens, the market ratios of stocks of the companies can be corrected to be maintained even in a great increase or decrease in the stock prices.

[91] Therefore, according to the fifth embodiment of the present invention, profit can be obtained through stock trading pattern using a volatility of stocks, and the investment ratio is adjusted by adaptively responding to a discrepancy between the market ratio and the investment ratio according to the change in the stock price, so that shortcomings of conventional volatility trading can be overcome.

[92] Hereinafter, a stock-futures/spot-stock composite trading method in the automatic stock trading system according to a sixth embodiment will be described with reference to FIG. 2.

[93] The stock-futures/spot-stock composite trading method is a composite trading method combining an arbitrage trading for stock price index futures with a spot stock trading involved with the arbitrage trading.

[94] For example, in the above-described buying arbitrage trading, if the real prices of the stock price index futures are higher than a theoretical price, that is, evaluated at a relatively higher price, the stock price index futures are sold, and at the same time, the spot stocks are bought. In this case, the bought spot stocks had rather be re-traded (spot stock trading) than be held until the maturity of the stock price index futures, so that additional profit can be obtained.

[95] Particularly, since only 15% of the buying amount of the stock price index futures needs to be paid as a margin, the remaining amount of 85% can be used for spot stock trading. Therefore, additional profit can be obtained. In addition, a profit cor-

responding to the interest thereof can also be obtained.

[96] According to the sixth embodiment for automatic composite investment trading, an investor inputs basis-ratio-section-based selling and buying positions through the trading condition input module 24. In addition, the investor selects companies included in the spot stock balance at the time of the arbitrage trading and trading methods for the companies.

[97] The market-situation checking/analyzing module 26 calcualtes a market basis ratio.

Based on the market basis ratio, the trading determining module 28 determines trading by using the arbitrage trading.

[98] The trading determining module 28 determines the trading by using the arbitrage trading according to the input section-based selling and buying positions and the calculated market basis ratio.

[99] The market-situation checking/analyzing module 26 checks the market situation of the companies included in the spot stock balance at the time of the arbitrage trading and analyzes the market situations in a manner suitable for the spot stock trading method selected by the investor.

[100] The trading determining module 28 determines trading according to the arbitrage trading based on the data of the companies included in the spot stock balance at the time of the arbitrage trading, which are output from the market- situation checking/ analyzing module 26.

[101] In the stock-futures/spot-stock composite trading according to a seventh embodiment of the present invention, a pair trading method is selected as the spot stock trading method.

[102] When the investor selects a pair of companies having a high correlation among the companies included in the spot stock balance at the time of the arbitrage trading through the trading condition input module, the market- situation checking/analyzing module calculates the stock prices and relative increase rates of the companies in the selected pair and outputs the results to the trading determining module 28.

[103] The trading determining module 28 determines selling or buying amounts corresponding to relative strengths of the increase rates of the companies and outputs the results to the placing/contracting checking module 29. The placing/contracting checking module 29 access a stock exchange system through the data communication network 50 to place a trading order and check the contracting thereof.

[104] In the stock-futures/spot-stock composite trading, the spot stock trading method is not limited to the pair trading method, but various investment methods including the volatility trading may be used. The system separately performs the arbitrage trading and spot stock trading such as pair trading and operates the separate adjustment system for combining and adjusting two trading methods at every time of occurrence of

trading signals corresponding to the methods, so that the two trading methods are not to be incompatible with each other.

[105] The adjustment system suspends the buying if the trading determining module 28 determines the buying the shares with an amount exceeding the investment amount. The adjustment system suspends the selling if the trading determining module 28 determines the selling the shares exceeding the remaining number of shares. Accordingly, it is possible to prevent short selling. Industrial Applicability

[106] According to the present invention, an automatic stock trading method and system capable of automatically monitoring and analyzing a change of a market and determining trading in consideration of trading conditions input by an investor and market situations and a storage medium storing an automatic stock trading program.

[107] In addition, according to the present invention, an automatic stock trading method and system capable of allowing an investor to select a trading method such as an arbitrage trading method, a pair trading method, a volatility trading method, and a stock-futures/spot-stock composite trading method and determining optimized trading in consideration of market situations according to the trading method and a storage medium storing an automatic stock trading program.