I think their website explains it here... "Why Sh

I think their website explains it here...
"Why Short Volume is Important
Daily short volume, as reported by FINRA, is very misunderstood. Most people think daily short volume is just that — the volume that bearish investors put on to add to their short positions. A short glance at the change for total short positions reported bimonthly to the NASDAQ debunks that belief. Short volume isn’t the same as short interest.
In truth, much of the short volume is due to market makers selling into the market a few fractions of a second/minute/hour before they close their position by executing a broker order. Due to the fact that market makers cover many of their positions seconds later, much of the short volume isn’t necessarily an indication of useful bearishness. The fact that a market maker is willing to sell and cover seconds later doesn’t do an investor holding the stock for the long term any good. The market maker could be bullish on the stock long term, and still be willing to short temporarily to satisfy a client request. Similarly, many market makers often have to go short in a fast market in order to fulfill their job of providing liquidity. Other market makers will widen their bid ask prices enough to get out of that scenario."

So as GNBT prices was moving up quickly, the market makers may have had to increase this short volume more than usual to keep liquidity in the market.

Disclaimer: Of course, all of this is my opinion and you should not make any investment decisions based on my opinion. I have not received any non-public information.