I used to idolize Michael Jordan as a youngster. Little did I know that I should've had posters of Wells Fargo (NYSE:WFC) CEO Dick Kovacevich on my wall. Anytime Warren Buffett owns a big stake in a company, you know there's something truly special about it. And at a recent Goldman Sachs financial services conference, Dick demonstrated why Wells Fargo is the best bank in the world.

Whereas Wells Fargo's biggest competitors, Citigroup (NYSE:C), Bank of America (NYSE:BAC) and JPMorgan Chase (NYSE:JPM) hardly seem to go a quarter without announcing a chest-thumping acquisition, and owe their big-bank status mainly to mergers, Wells Fargo quietly continues to grow organically and do the little things -- like sell more products to its customers.

In the conference call, Dick talked about how Wells Fargo currently sells 5.1 products to its average consumer household, up from three in 1998. He also thought that the cross-selling ceiling was a stunning 14-16 products. Although that seems a bit much, currently 19% of Well Fargo's customers have eight products, up 50% in the past five years. Wells Fargo's core product sales have increased a truly impressive 13% annually since 2001.

Perhaps Wells Fargo's greatest weapon is its status as the No. 1 mortgage originator, with a $1.3 trillion mortgage-servicing portfolio. Naturally, customers tend to trust and want to do more business with the bank that services their most important asset, and Wells Fargo happily obliges. The average mortgage customer has 7.7 other products with Wells, in contrast to the overall average of 5.1.

So what lessons can be learned from Wells Fargo's success? Dick mentioned customer loyalty as a key competitive differentiator. Wells Fargo conducts 50,000 telephone interviews with customers per month. That's a lot of phone calls. The company was also the only mortgage lender in the top five in both volume and customer service. Usually, as banks get bigger, customer service becomes more impersonal and satisfaction ratings lag. Not so at Wells.

When asked the secret of Wells' success, Dick talked about execution and long-term investing. Wells' strategy is hardly a secret. All a customer has to do to figure it out is walk into one of its banks and see that its plan is to sell more stuff to its customers, and keep the customer happy. The hard part is that the strategy involves thousands of details that must be performed on a daily basis. Like a diet, the strategy is simple; it's the actual implementation where people get mixed up.

The second key to success is to invest for the long term. Wells has invested heavily in its sales force, and acknowledges that it's usually a three-year process to get a banker up to speed. Wells has also consistently made long-term investments that required painful up-front expenditures -- the kind that don't win kudos on Wall Street, but build the company's long-term moat. The company was first to enable online banking and bulk checking, and it's currently rolling out web-enabled and envelope-free ATMs. Although execution and long-term investing aren't as sexy as making billion-dollar acquisitions, Wells Fargo seems to have a penchant for putting billions of dollars in its shareholders' pockets, rather than that of an acquisition target.

Further trips to the Foolish wells:

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Fool contributor Emil Lee is an analyst and a disciple of value investing. He doesn't own shares in any of the companies mentioned above. Emil appreciates comments, concerns, and complaints. The Motley Fool has a disclosure policy.