Hi, I've been trading long-only strategies with IB for months, and am now diversifying into a short strategy. It's a little scary dealing with the extra "power" that IB gives you, in terms of giving you more choices in terms of shortable stocks... but also charging you up the butt in borrowing fees, in some incidences. I think I have a good grasp of the borrowing rates, which you can find by looking under account tools. But how significant is the "shares available" number? If the number goes to zero, does that imply IB is likely to force me to buy-in to cover my short position? If I expect to hold a position for 3-4 weeks... what's a safe minimum threshold for "shares available"? And if I drop beneath the threshold, there's a realistic risk that IB is going to force me to cover? Any anecdotes out there that anyone can share with me? Thanks!