The value of your investment will decrease, but you will not owe money. If you buy stock using borrowed money, you will owe money no matter which way the stock price goes because you have to repay the loan.
Did Steve Jobs leave his daughter any money?
Lisa Brennan-Jobs, now a 42 year old author and a Harvard graduate, had a different experience growing up with her father than her half-siblings. After his death, Steve Jobs did make sure to leave Lisa with a multi-million dollar inheritance.