This is JUST Interactive Brokers availability. Each broker has its own inventory avail for shorting, I believe... Interactive Brokers however is only broker that shows inventory totals like this , as far as I can tell... I am not an IB customer and I do NOT short stocks so I am not sure how many would be total inventory for all brokers to short...
This was from this past Saturday:(see below) It has dropped to 200,000 shares as of last night, Meaning someone(s) opened a 500,000 short position in SPNG? (Saturday 06/13/09) Symbol: SPNG Availability: 700'000 Exchanges: PINK, ARCAEDGE, NITE, IBSX, OTCBB