(Reuters) -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.

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.

($1 = 7.1993 Chinese yuan)

(Reporting by Zhang Yan and Brenda Goh; Editing by Edwina Gibbs)