If you take a look at the Warren Buffett analysis spreadsheet from his 2017 letter to investors, you will soon find out that a lot of the gains produced from 2017 were actually from a change in the US tax code with the changing leadership and Donald Trump. 60 billion dollars was made in the 2017 fiscal year for Berkshire Hathaway with Charlie Munger, however, half of this, 30 billion dollars, was due to the change in tax code.
Warren and Berkshire Hathaway, located in Omaha, Nebraska, own about 12 different stocks as of 2017. Recently, Berkshire Hathaway bought seventy-five million shares of Apple Incorporated, the famous technology company based out of California. In fact, the type of stocks that Berkshire Hathaway owns are varied. They range across all different sectors in order to diversify risk, and include the likes of the American Express company, BYD, U.S. Bancorp, Goldman Sachs, and Wells Fargo, to Delta Airlines and American Airlines; These are just a few examples of the stocks that Berkshire Hathaway owns.
Much of the biggest gains that Berkshire Hathaway was able to make were due to the 2008 Market drop which was due to the overvalued junk bonds which were being sold as high-grade Bonds in the real estate market. During this time, Berkshire Hathaway was able to buy many properties and even form a real estate branch of its company, Berkshire Hathaway Home Services.
A careful analysis of the spreadsheet in 2017 shows that each company stock which Berkshire Hathaway owns never exceeds 25% ownership in the company.