Berkshire Hathaway, controlled by guru investor Warren Buffet, bought 80.5 million shares on April the 9th, 85.37 million shares on April the 11th and 31.41 million shares four days later, all around the $HK1.66 per share mark.
The company now controls around 9.1 percent of PetroChina's publicly traded stock with the Chinese government holding 90% of the entire company.
The foray helped to push PetroChina stock up 3.6% on Monday to a nine-month high.