A regulatory filing has revealed his purchase of 180,000 Chevron common stock occurred on Monday at an average price of $108.10 each - with the stock down 14% in the last 12 months due to the ongoing oil downturn.

Stumpf had previously owned just 1885 shares directly and 18,208 through a family trust with the new buying spree giving him more than 200,000.

The director's motivations are not known although significant insider buying is typically seen as a bullish indicator by stock market enthusiasts.