Either/both on number of issues and/or number of shares... there might be a correlation to market turns...
1st of all u did something that many posters don't do. you checked to see whether there was as existing on the subject. +1. this thread was reactivated after 5+ years. it might be a record of sorts. kudos to you. most likely one of the files that they received from the people who have lending inventory was corrupted.
I short regularly at IB and have NEVER had a problem. I simply use a filter for daily avg vol over 1.5 million shares and price over 10. At less than that volume or price, I wouldn't want to be short even if I could get it.
well..it is what it is..every morning i download their shortable list and this information is based on info they provide. i'm not making this shit up..on top of that,shortly after open i've noticed that many of stocks that suppose to be shortable according to IB list are not. dunno what you trade,but this what i got today. about 30% reduction in short list compared to yesterday. happens in past few times,right when market goes down.. you can check this yourself next time. right now the list is back to "normal" with 10K+ securities on it. but this morning it was 7K+ http://www.interactivebrokers.com/en/p.php?f=shortableStocks
I've had great luck with Cobra Trading and their willingness to make the calls to work and find me shares. IMO they are one of the best in this respect, however I'd just give them a call or IM them next time you get shut out at IB and want to see if someone else has shares.
who knows, maybe they reserve the hard to borrows for themselves (market making side) when things get dicey. or maybe the street reserves shorts for the same reason. not surprising.