Let's do a little investment simulation. Don't worry - I'll do the maths. Nomusa has a R5,000 personal loan and a R20,000 share portfolio. Her net worth is R15,000 (R20,000 share portfolio minus the personal loan). If the stock market goes up by 10%, Nomusa makes R2,000 (R20,000 multiply by 10%) and her net worth goes up to R17,000 (R22,000 in the portfolio, minus the R5,000 loan).