Bourla's sale was conducted under Rule 10b5-1, established by the SEC, allowing the corporate insider to sell a predetermined number of shares at a predetermined time. A Pfizer spokesperson told Axios that the CEO's predetermined trading plan was formed in August. 

Despite the sale being perfectly legal under Rule 10b5-1 to avoid accusations of insider trading, the optics aren't great for Bourla, who still managed to top-tick the 52-week-high on the sale on news day. One can argue that he couldn't have known the results of the vaccine trial months ahead of time. And while all this is coming out just days after a critical US election, though it's not clear if that was a trigger.

Other pharmaceutical companies such as Moderna, also producing a COVID-19 vaccine, experienced similar insider selling over the summer around vaccine news - where insiders dumped tens of millions of dollars of stock. 

Under the cover of Rule 10b5-1, corporate insiders at some pharmaceutical companies are already running for the exits by dumping their stock, of course, it's easier to commit to pre-plan sales of stock when you know you can pump the price by simply publishing a press