For the fifth time since its last shareholder meeting, Berkshire Hathaway (NYSE: BRK.A) has announced that it has sold more shares of Petro-China ADR (NYSE: PTR), trimming back its position from 7.29% to 6.97%.

Berkshire is trading at $121,500 per share as I write this story. The highest price stock on any exchange keeps moving higher as Warren Buffett continues to amaze. Over the last five years he has become a utilities mogul, and this year you can add railroad tycoon to the Oracle of Omaha's many characterizations.

It is not clear why he is selling shares, since his investment is up six-fold in the last five years. However, Berkshire's stake in Petro-China was one of the few areas of contention to ever be raised at a shareholder meeting. This year, because of PTR's business relationship with Somalia Sudan, and the human rights violations in the Darfur region, many shareholders questioned this holding. Buffett seemed to imply he did not want to overtly mix business and politics and thought more could be done from the inside than the outside. Given Buffett's desire to make his moves quietly, it is very possible that he has decided to trim his shares slowly to accommodate concerned shareholders, while not wanting to create negative pressure on the stock price.