BYD Co, China’s biggest electric car maker, said third-quarter net profit likely more than quadrupled due to robust sales and a better product mix, sending its shares surging.

It estimated that net profit for the July-September quarter came in between 5.5 billion yuan to 5.9 billion yuan ($765 million-$820 million), or an increase of 333% to 365.1% from the same period a year earlier.

BYD’s Hong Kong shares gained 4% on Tuesday morning while its shares in Shenzhen climbed 5%.

The company, which is 19% owned by Warren Buffett’s Berkshire Hathaway, said in a filing late on Monday that improved cost controls had also contributed to the jump in earnings.

Toyota to start selling small electric sedan in China by year-end

Government incentives have helped sales of electric vehicles surge in the world’s biggest auto market.

BYD’s combined sales of pure electric and hybrid plug-in vehicles increased 250% in the first nine months, easily outpacing a 110% rise for the overall EV segment.