Systematic Equity Plan or SEP allows you to invest small sums of money regularly in selected stocks to reap good returns. You can buy shares within a fixed amount at regular intervals as per your requirement. Systematic Equity Plan (SEP) or SIP in stocks work similar to SIP in mutual funds in the sense that it allows an investor to invest systematically in direct equities by buying a specific stock in specific number after a specified interval or stipulating a limit in respect of the maximum amount for which stocks can be purchased after a specified interval.