Berkshire Hathaway says the audit committee of its board has released a report about Sokol's trading that says the former executive's purchases of Lubrizol shares violated company policies.

Furthermore, Sokol's “misleading, incomplete disclosures to Berkshire Hathaway senior management concerning those purchases violated the duty of candor he owed the company,” says the report from the committee, which goes on to use Sokol as an example of the importance of adhering to company policies.

Sokol was “encouraged” to scout for potential acquisition opportunities in 2010 and, after meeting with investment bankers, Sokol asked them to give him information about companies in the chemical industry. The bankers came back with a list of 18 companies, which were narrowed down by Sokol to three, including Lubrizol.

What followed was a series of buying and selling of Lubrizol shares by Sokol during late 2010 into 2011, says the report.

In January, when Sokol told Buffett about Lubrizol, he mentioned he owned the stock but did not tell Buffett about the timing of the buys or about the fact he bought the shares after arranging a meeting with Lubrizol's chief executive. According to the report, Buffett thought Sokol had knowledge of Lubrizol because he was a stockholder, not because investment bankers brought the company to Sokol's attention.

Buffett did not learn investment bankers were involved in introducing Lubrizol to Sokol until they congratulated Buffett on an announcement in March that Berkshire and Lubrizol had plans for a merger.

When Sokol resigned, for reasons he said were personal, he said he was doing so for reasons unrelated to the trades.