Berkshire Hathaway, the investment firm run by Warren Buffett, has reduced its stake in PetroChina once again, according to filings made to the Hong Kong Stock Exchange on Monday. The company's stake has fallen from 7.29% to 6.97% following the sale of 66.6 million H-shares on September 21 at an average price of HK$11.99 (US$1.55). It is the fifth time since July that Berkshire Hathaway has publicly disclosed the sale of PetroChina shares, the Wall Street Journal reported. Analysts said the sale was most likely a move to consolidate profits. PetroChina shares closed down 3.4% at HK$14.10 (US$1.82), having risen 15% since mid-July when Buffett made his first sale. The stock has been in demand due to strong oil prices and PetroChina's aggressive explorations as well as its impending listing in Shanghai. Berkshire Hathaway remains the second-largest shareholder in PetroChina after the oil firm's parent group.