Warren Buffett’s Berkshire Hathaway Inc (NYSE: BRK-A) faced a missed opportunity by selling its shares in Costco Wholesale Corporation (NASDAQ: COST) during 2020. This move, which ended a long-term investment in the retail giant, resulted in a potential loss of approximately $1.5 billion in gains, according to Business Insider. The shares, sold for an estimated $1.3 to $1.6 billion, would be valued at around $3 billion in today’s market. This substantial financial miscalculation occurred as Costco’s stock prices climbed near-record levels. Since Buffett’s exit, the company’s stock has soared b…