Investors shouldn't unthinkingly follow Buffett, or any other billionaire money manager, into Amazon or any other stock. However, Amazon is a top stock with robust opportunities trading at an attractive valuation, and if you have $500 available today, Amazon is an excellent choice.

Warren Buffett is stockpiling cash. His Berkshire Hathaway holding company continued to sell more than it bought in the third quarter when it offloaded a quarter of its stake in Apple, regulatory filings revealed Thursday.

Plenty of big-time investors have made a name for themselves over the years, but arguably none have become as big of a household name as Warren Buffett. Thanks to personal achievements and the success of his company,

There is one stock he has never sold since buying in 1991, though: American Express ( AXP -0.20%). Buffett owns over 20% of the credit card issuer and bank, making it the second-largest position in the Berkshire Hathaway portfolio. The position trades at a value of $40 billion as of this writing.