(Reuters) – The U.S. Securities and Exchange Commission is investigating whether recent stock sales by Tesla Inc Chief Executive Elon Musk and his brother Kimbal Musk “violated insider trading rules”, the Wall Street Journal reported on Thursday, citing people familiar with the matter. According to the report, the investigation began last year after Kimbal sold shares of the electric carmaker valued at $108 million, a day before Musk polled Twitter users asking whether he should offload 10% of his stake in Tesla. Kimbal Musk did not know about the Twitter poll ahead of it, Elon Musk told the F…