In a US regulatory filing, Berkshire, whose chief executive is Buffett, says itbought $524m worth of Suncor stock in the second quarter. As of 30 June it owned17.76 million shares of the company.

Suncor is best known as a major producer of crude from Alberta’s oil sands fromwhich it obtains most of its output. Suncor also has sixoperating wind farms totaling 255MW – three in Alberta (148MW), two in Ontario(96MW) and one of 11MW in Saskatchewan.