Why did Dr. Taylor sell now? Perhaps he doesn't expect an increase in SP for a while. But, I think the opposite is more true: that he doesn't expect price to decline significantly in the next while due to news or events. If he sold now, knowing negative news is coming soon then he would be suspected of insider trading once the negative news was released.

Also, whatever his personal needs for the $$ are, it's better that he sold in one big chunk now, then in several smaller sales spread out over several months where there would numerous headlines on the quote screen reading "Disposition of Shares by Chief Scientist".

I like how the company announced this proactively before markers appeared and also the explanation from GT himself. I've not met the man personally, but I get the impression he didn't want to sell right now but rather had to. GLTA