When a stock's bid is on a downtick, shorting is not possible. However, I've seen many times where the downward momentum slows and people on ISLD start crossing/locking the market, but the actual bid is still on a downtick. Am I able to short into the ISLD crosses/locks? Of course, I'd rather wait for the small rally to start topping before I short, but I'm curious as to whether it's possible to short in the above situation.