Simply buy and sell stocks. If a stock has a value of at least 100, it has a chance to pay dividends (give you money) each turn. If a stock reaches a value of 200, it will split (value set to 100, number of shares doubled). If a stock reaches a value of 0 it will be delisted (all shares are worthless), and a new company will replace it (with a starting share value of 100).
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