Why so many IB stocks unshortable today?

[ej420]

I noticed the same today on stocks like HAL, BNI and others. It lasted from market open to about 10 EST. Is this normal? The stocks that were unavailable were quite liquid. How often does something like this happen.

Also, I wasn't set up properly at the time, but did tickGeneric() properly report that those stocks were not shortable?

 

[HotTip]

So I called IB earlier and the guy said that because it's earnings season it could result in a lot of shorting that causes inventory to runout. Not sure how true this is, considering that I've traded through earnings seasons for the last 7yrs and have never run into this problem before. Either way, things slowly got back to normal a couple of hours ago.