Tesla shares jumped more than 8% in premarket trading on Monday after a regulatory filing showed that CEO Elon Musk had purchased nearly $1 billion worth of the electric-vehicle maker's stock last week.

Musk disclosed buying 2.57 million shares in open-market transactions on Friday, paying between $372.37 and $396.54 per share, according to the filing.

Tesla shares jumped more than 7% on Friday, extending solid gains from the previous session. The stock, which has fallen about 2% so far this year, is on track to record a third straight session of gains if premarket moves are sustained.

Investor sentiment on the automaker has been dampened by faltering EV demand, as well as Musk's focus on politics.

On Friday, Tesla board chair Robyn Denholm dismissed concerns that Musk's political activity had hurt sales and said the billionaire was back "front and center" at the company after several months at the White House.