Over the weekend, Warren Buffett released his highly anticipated annual letter, which reflects his consistent investment philosophy year after year. For investors, this serves as a valuable reminder to revisit his timeless investment principles. I'll outline the key lessons from his letter. 1) Be business pickers, not stock pickers The stock quote is much easier to read than financial statements so many investors tend to focus on the share price movements and get too emotionally attached to the gains and losses in their investments, causing them to make poor buy and sell decisions as a result. Buffett provides an excellent example of the importance of focusing on fundamentals: "The company’s operating earnings – our term for income calculated using Generally Accepted Accounting Principles