Simply put, the interest you're paying on your loans is eating into any gains you have in the stock market. So, figure out how much you're paying in interest and consider the feasibility of paying off some of the loan. Also figure in if you would be selling the stock at a profit or a loss.
Generally speaking, a home loan is typically long-term, with a high principal. I believe the consensus is that it is typically not worth paying down extra on it. A car loan, though, is much shorter term, with a lower principal. It may be worth it to pay that down.
I would certainly consider paying down the loan with 10% interest, even without running any numbers.
What about doing this without selling stock? The reason I suggest that is that you should not sell the stock unless you truly need the money or for some material reason(s) related to the company, the market, etc. (Of course, one other reason would be to cut losses.)
Unless I was looking to sell some stock anyway, I would try other ways to come up with the money to pay down the highest interest loan, at least. If you are thinking of selling stock to pay down debt, definitely run the numbers.