While I'm not suggesting it's a good strategy to short continuously, unless you short a hard to borrow stock, the borrowing fee for shorting a stock is typically much lower (as in 0.25% yearly) than the interest you can get on the cash you get to hold after short sell a stock (should be 4.5%-5% with the current fed funds rate).<p>So, other than the transactions fee, shorting a stock that doesn't move is a way to arbitrage the spread between the Fed funds rate (minus 0.5% or so depending on your broker) and the stock borrowing rate.