I have seen IPIX falling on friday the whole day and I was not able to borrow it at IB for the whole day. Where does all the additional volume come from? Probably from shorting, right? So how is it possible, that IB doesn't have them available? I would really like to have official answer from IB person at ET. On the other hand, which brokers did have IPIX available for shorting on friday? Please help, fellow traders.