It is updated every 2 weeks so it's a little behind, but you can also check the short interest on the FINRA site, it's the same. As to the after hours bid/ask you see on here it's meaningless.
Let me clarify this so it doesn't sound like the MM's are "shorting" the stock.
What happens is when shares are swapped around between owners before shares are cleared is that the MM's are "short" the shares until they are cleared thus giving the impression that they are "shorted" when the MM's just simply need to wait for shares to be cleared before truly assigning them over to the new owner.
What throws people off is that when they are cleared they don't reconcile the shorted shares since it can't be accounted for twice.
Yes, MM's short in some aspect but not in the nefarious way that every OTC trader thinks.
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