Berkshire Hathaway added more than 10.8 million shares of Suncor, an energy company based in Calgary, Canada.
Shares of Suncor jumped as high as nearly 4 percent in after-hours trading on Thursday.
The conglomerate also revealed 4.175 million new stake in software company Red Hat.
Bershire boosted its investments in many U.S. banks last quarter including Bank of America, U.S. Bankcorp, PNC, Bank of NY Mellon and J.P. Morgan.
It dissolved its 41.4 million-share stake in Oracle and decreased its holding of Apple shares to 249.5 million.