The affair relates to Lubrizol Corp, in which Sokol bought shares last December. He then went on to sell them before buying more shares in early January. Afterwards, he suggested to Buffett the idea of buying the company.

Sokol did make a “passing remark” about owning some Lubrizol shares, but Buffett did not know the extent of his ownership, nor press Sokol on the matter. He discovered Sokol’s full interest on 19 March.

Berkshire Hathaway entered into a definitive agreement to buy Lubrizol on 14 March, in an all cash transaction valued at around $9.7 billion.

“Though the offer to purchase was entirely my decision, supported by Berkshire’s board on 13 March, it would not have occurred without Dave’s early efforts,” a statement from Buffett said.

Furthermore, Buffet said that as late as 24 January he had doubts about the acquisition, favoring another substantial acquisition for which MidAmerican – a Berkshire subsidiary – had made a bid.

He was persuaded to go ahead following a dinner conversation between Sokol and James Hambrick, the chairman, president and CEO of Lubrizol, on 25 January, the details of which Sokol reported back to Buffett.

The 96,060 shares Sokol purchased between the 5 and 7 January would have made him a profit of some $2.98, based on the company’s share price during that period and the price Buffett agreed to pay for it.

On his reasons for resigning, Sokol cited a desire to create a family business which would leave a legacy for his descendants and generate resources to fund his philanthropic interests.

Buffet said Sokol’s resignation came as a surprise, and that he did not consider the Lubrizol purchases in any way unlawful. He did however say that Sokol had talked of resigning on two previous occasions, but on this one he “did not attempt to talk him out of his decision.”

Buffett has been a vocal champion of transparency in the corporate and financial world, and in his statement said he had “held nothing back.”