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https://www.investopedia.com/ask/answers/021615/what-difference-between-berkshire-hathaways-class-and-class-b-shares.asp
Berkshire History and the Introduction of Class B Shares
More than 20 years ago, Berkshire Hathaway was content with its highly valued, single class of stock. But the market was demanding a lower-priced, more common-stock nibble at the Berkshire pie, given that shares were trading for around $30,000 at that time. So in 1996, Warren Buffett, CEO of Berkshire Hathaway, and the board responded by issuing 517,500 shares of Class B shares, offering the ability to invest in the company for, initially, 1/30th the price (and equity) of a Class A share of stock.3
A 50-to-1 stock split in 2010 sent the ratio to 1/1,500th. In other words, each share of a Class A common stock was convertible at any time to 1,500 shares of Class B common stock.4
Class B shares carried correspondingly lower voting rights as well (of the voting rights of a Class A share 1/200th of the per-share voting rights. later changed to 1/10,000th), and Buffett marketed Class B shares as a long-term investment and as an open-ended offering, so as to prevent volatility as a result of supply concerns.4