How many brands can compare to Coke?Warren Buffett, often referred to as the "Oracle of Omaha," has a knack for backing companies that stand the test of time. Take American Express, for instance. His firm, Berkshire Hathaway, first invested $300 million in the company in August of 1991. Over the next four years, Buffett continued to purchase shares, raising the total investment to $1.3 billion by 1995. Today, the stake is worth more than $36.5 billion, paying a yearly dividend worth more than that initial i ...