If you're going to be a savvy investor, you need to know about -- and read -- quarterly earnings reports that companies issue.

Most publicly traded American businesses are required to publish their financial performance four times a year. Once a year, companies issue an annual report and, along with it, a more-detailed 10-K report. In the intervening quarters, companies issue 10-Q reports. (Thus, over four quarters, you'll see three 10-Q reports issued, followed by the annual report/10-K.)

The 10-Q summarizes quarterly performance. While it's fairly abbreviated, it can still be extremely enlightening. The 10-K reviews the year's results in much more detail and features a lengthy discussion of the firm's operations and challenges as well.

Public companies also often hold a quarterly phone call between management and Wall Street analysts. Many open these calls to the public, and websites such as CCBN.com provide online access to numerous corporate conference calls. (To access CCBN data, go to our Quotes & Research area, and under "Tools & Resources," click on "CCBN Conference Calls.")

Usually, you'll be listening to a recording of the call, not the live call. Regardless, this is a terrific way to stay in touch with your holdings. You might even learn a lot from things such as a CFO sidestepping questions or a CEO getting defensive at some queries. If your company isn't opening up access to its quarterly call, give the company a jingle, express your displeasure, and remind it that the Securities and Exchange Commission (SEC) frowns on selective disclosure of material information.

To learn more about investing Foolishly, visit our Fool's School and our Investing Basics area. Or check out some of our inexpensive and well-regarded online how-to guides (which feature money-back guarantees). You can also learn all about brokerages and find one that's right for you in our Broker Center.