A shareholder letter is a letter written by a firm's top executives to its shareholders to provide a broad overview of the firm's operations throughout the year. The letter generally covers the firm's basic financial results, its current position in the market, and some of its future plans. The shareholder letter is generally written once per year and is included in the beginning of the firm's annual report.
Taobiz explains Shareholder Letter
The shareholder letter can be a good first stop towards getting a broad overview of a firm that you are analyzing for investment. However, it is important to understand that the shareholder letter, along with many other parts of the annual report, is normally written in a way to put the company's operations in the best possible light. Investors will want to take the information in the shareholder letter with a grain of salt and be sure to delve more deeply into the firm's financial results and perform independent research on the company and its industry before drawing conclusions.