AlanC, Carrying cost of money is the initial investment for those shorting. If their margin fees are say $100 for a short position they have open, and when they close it, they make $1000, they have made a 900% profit on that $100 investment. Sure they have downside risk if they are forced to cover at a loss. But when there are profits, there are profits which are easier to come by than pumping a stock up.
Also, market makers selling endless shares which they never borrow or intend on borrowing, what are their profit margins?
Please research all stocks before investing. My posts are my opinions and are not buy or sell recommendations. Always force market makers to cover their shorts above what you paid. Build wealth for fellow iHub'ers!