The U.S. securities regulator has decided not to take action against David Sokol, a former top executive at Warren Buffett's Berkshire Hathaway Inc, and has completed its probe into possible insider trading, Sokol's lawyer told Reuters. In 2011, Buffett said Sokol violated the company's insider trading rules to score a $3 million windfall profit on shares of U.S. chemicals maker Lubrizol, which rose by nearly a third after Berkshire Hathaway announced it would buy the company. The U.S. Securities and Exchange Commission (SEC) began investigating Sokol's investment in Lubrizol shortly after Sokol resigned from Berkshire Hathaway. Sokol's lawyer Barry Wm. Levine told Reuters late on Thursday that he was informed that the SEC had wrapped up its investigation and decided not to take action against Sokol. "SEC has terminated its investigation and has concluded not to bring any proceedings against Sokol," said Levine, a lawyer at legal firm Dickstein Shapiro.