Bill Gates has sold another 20 million shares of the company he co-founded, driving his portfolio under the 300-million mark for the first time, according to regulatory filings. Over a five-day span from July 24 to July 30, Gates sold the shares at prices ranging from $43.45 to $44.54, turning the holdings into $882 million in cash. The U.S. Securities and Exchange Commission (SEC) published the sales documents between July 28 and July 31.