The most expensive stock ever sold is Berkshire Hathaway Inc. Class A shares (BRK.A). As of October 13, 2023, it is trading at over $563,000 per share.

Berkshire Hathaway is a conglomerate holding company led by legendary investor Warren Buffett. The company has a wide range of investments, including insurance, railroads, utilities, and consumer goods. Berkshire Hathaway is known for its long-term investment horizon and its focus on quality businesses.

There are a few reasons why Berkshire Hathaway stock is so expensive. First, the company has a long history of success. Buffett has been at the helm of Berkshire Hathaway for over 50 years, and during that time, the company has generated an average annual return of over 20%. Second, Berkshire Hathaway has a very strong balance sheet. The company has over $100 billion in cash and equivalents, and it has no debt. This gives Berkshire Hathaway a lot of flexibility to invest in new opportunities and to weather any economic downturns.

Another reason for Berkshire Hathaway's high stock price is that it is a very rare commodity. There are only 660,000 Class A shares outstanding. This makes Berkshire Hathaway stock one of the most illiquid stocks on the market.

Finally, Berkshire Hathaway stock is expensive because it is a status symbol for many investors. Owning shares of Berkshire Hathaway is a way to show that you are a sophisticated investor and that you have confidence in Buffett's abilities.