With this computational module you can compute the return on an (equity) investment. The calculator takes the following effects into account:
Transaction costs for buying and selling instruments on the stock market,
debet interest on a margin account or on any other loan that provided the money to invest with,
dividend and the ex-dividend date,
There are people who are buying shares and selling them the same day, after a common upwards variation in the share price: day-traders. From the bottom field (yearly ROI) one can conclude that their returns can be quite high.
See this page for an example computation with this calculator. Furthermore the Trading Simulator is the extension of the calculator below for multiple transactions, multiple instruments and/or multiple dividends.