[Editor's note: This story was updated at 8:50 a.m. CST Feb. 15.]

Warren Buffett’s Berkshire Hathaway Inc. (NYSE: BRK.A) said Feb. 14 it had taken a fresh stake in Suncor Energy Inc. (NYSE: SU) for the second time in about six years, sending the U.S.-listed shares of the energy major up 4% in after-market trading.

Suncor, Canada's biggest oil and gas company headquartered in Calgary, Alberta, specializes in production of synthetic crude from oil sands. The company is considered one of the safest Canadian energy companies to invest in, given its integrated structure and diversified business mix.

Berkshire's investment puts the Buffett stamp on Suncor and could be seen as a positive for the Canadian energy sector. The move comes at a time when global investors have been pulling away from Canada because of its carbon-intensive oil sands and struggle to approve pipelines.

Berkshire said in a filing with the U.S. Securities and Exchange Commission that it has a stake of 10.8 million shares in the company, representing about 0.7% of Suncor's total outstanding shares, according to Eikon data from Refinitiv.

Ahead of the news on Feb. 14, Suncor's shares had shed 17.3% in the last six months, due in part to Alberta's decision to force mandatory production cuts last year.

The new position comes more than two years after Berkshire sold its stake in Suncor. Berkshire took a position in Suncor in 2013 and exited its stake in 2016.