Berkshire Hathaway is a company that defies definition, but CEO Warren Buffett is preparing now for something big.

Warren Buffett’s Berkshire Hathaway (NYSE: BRK.A) (NYSE: BRK.B) is often considered a reliable stock for conservative long-term investors. The conglomerate is led by Warren Buffett, who famously said his favorite holding period for a stock is "forever.

Warren Buffett has purchased $345 million worth of Berkshire Hathaway stock in the June quarter. This brings the year-to-date total to $2.6 billion and nearly $78 billion since 2018. Regular buybacks suggest that Buffett believes Berkshire stock is often undervalued.

Berkshire introduced the Class B shares in the 1990s to make the stock more affordable to smaller investors. However, with the advent of fractional shares, investors can now purchase as little as they want of the Class A stock,

Chubb runs a business model very similar to Berkshire's. It was strange that Buffett would opt to buy shares of a close competitor instead of simply repurchasing Berkshire stock directly. Might Buffett believe that Chubb could become the next Berkshire -- signaling a huge growth runway ahead?