Is he a social as well as a financial sage? Following months of pressure from human rights activists perturbed at PetroChina’s activities in Sudan, Warren Buffett is selling shares in the mainland oil and gas giant. On Tuesday it emerged that the billionaire investor sold a further $100m worth of shares, his fifth disposal since July.

On the face of it, it looks as if Mr Buffett’s shareholders can rest assured that their guru has not gone soft. PetroChina, the biggest of China’s oil and gas trio, has performed fabulously. Its Hong Kong-listed shares are up 29 per cent so far this year, and almost four times the level at which the UK’s BP exited in 2004. Mr Buffett is selling shares at about seven times the amount he paid for them in April 2003 and quitting one of the world’s priciest integrated oil and gas stocks, trading on about 16 times this year’s consensus earnings. Superior production helps justify some premium but PetroChina’s biggest earnings fillip – higher oil prices – also benefits the rest of the industry and, in any case, is not a given. Excitement over acquisitions may be overdone, since PetroChina is a $325bn goliath requiring a mega-deal to move the needle.