In other words, history has shown that when Buffett's prized valuation tool moves well beyond the bounds of its long-term average, trouble follows for Wall Street. This may be why the Oracle of Omaha has been a net seller of stocks for eight consecutive quarters at Berkshire Hathaway, to the tune of $166.2 billion.

According to the Bloomberg Billionaire Index, Warren Buffett’s net worth has increased by $6 billion this year. That moves him to $148 billion, just behind his friend Bill Gates, who co-founded Microsoft and has a net worth of $166 billion.

Warren Buffett, one of the richest men in the world, has a vast investment portfolio that includes many of today's biggest companies. Through his experience, he has accumulated various assets