The transactions weren't really sales.
HTGC has a restricted stock bonus plan, where they promise to give each exec a set number of shares if they stay with the company for a set period of time.
When that time period is up, the restricted stock vests and becomes taxable to the executives. HTGC is required to get enough cash from each exec to cover he withholding taxes. But instead of coming up with the cash, HTGC's plan allows HTGC to hold back enough of the restricted stock to cover the withholding taxes. That is what happened, and the shares that the company withheld were reported as disposed (not sold) on the SEC form. The code on the SEC form (code "F") shows that this wasn't a sale, but rather the withholding tax that I just explained.
So if HTGC granted the CEO 100 restricted shares, the grant would be recorded as an acquisition (not a buy) by the exec on the SEC Form 4. Because the shares are restricted, the company would hold onto them. Then, when the shares vested, the company would hold back say 30 of the shares to cover the withholding tax and those 30 shares would be reported as disposed. Which is what happened.
This month, the company granted a bunch of new restricted stock shares to the execs and they filed SEC forms to record that. Again, someone looking quickly might think these were buys, but they weren't.