NEW YORK (TheStreet) -- When it comes to Warren Buffett and Berkshire Hathway , the numbers are often mind-boggling: $70 billion net worth; shares that sell for hundreds of thousands of dollars each; dozens of portfolio companies and more. To top it all off, Berkshire Hathaway is getting even bigger: Regulatory filings late Friday showed the company expanded its stake in Phillips 66 to 10%, worth about $4.5 billion at current prices.