At its all-time high closing price on August 4, 2017 of $270,000 per Class A share, Berkshire Hathaway (NYSE:BRKa) has a market capitalization of $444 billion, which is the sixth largest company.
The six largest companies by market capitalization are:
(1) Apple (NASDAQ:AAPL) ($815 billion)
(2) Alphabet (NASDAQ:GOOGL) (Google) ($655 billion)
(3) Microsoft (NASDAQ:MSFT) ($561 billion)
(4) Facebook (NASDAQ:FB) ($493 billion)
(5) Amazon (NASDAQ:AMZN) ($474 billion)
(6) Berkshire Hathaway ($444 billion)