While you can't see Buffett's other seven high-yielding dividend stocks in Berkshire's filings, the company, in essence, has a "secret portfolio" in New England Asset Management (NEAM), which is not directly managed by Berkshire. In 1998, Berkshire came to own NEAM via its acquisition of General Re, which bought NEAM in 1995.

An exchange-traded fund keyed to Warren Buffett’s Berkshire Hathaway equity portfolio has attracted nearly $250 million since its inception in March. The VistaShares Target 15 Berkshire Select Income ETF holds 21 stocks—20 in Berkshire’s portfolio plus 10% of its assets in Berkshire’s Class B shares.

Perhaps that’s one reason stocks are selling off globally this morning. While most indexes in Asia and Europe remain near their all-time highs, there is broad-based but mild selling in all of them.