I don't believe INTL or GTSM are shorting. ASCM was shorting yesterday (they seem to show up and short us every day a PR is dropped), but in regards to INTL, I believe they either have a large sell order or a pre-arranged transfer of shares in a specific pps range.
With GTSM, 99% of the time they are just retail... That doesn't mean that they can't short us, just that I don't believe they are. As far as retail goes, I don't believe there are many shortable shares out there, and retail cannot naked short...