Some insight into the holdings of large hedge funds is provided via SEC Form 13F filings. These quarterly reports are filed by institutional investment managers like hedge funds and also including investment advisers, banks, insurance companies, some pension funds and corporations that have discretion over more than $100 million in Section 13(f) securities. Section 13(f) securities are defined by the SEC online here, and generally include investments that are listed on American exchanges such as NYSE, AMEX and Nasdaq. (Note that disclosure of securities traded solely on foreign exchanges, private investments, short positions, and in mutual funds is not required.) Investment vehicles that meet these requirements must report the names and number of shares they own as well as the market value. Click on the PDF below to see an example of a Form 13F:
Form 13Fs can be found on the SEC's Electronic Data Gathering, Analysis and Retrieval (EDGAR) database, which is available to the public for free online here. To search for form 13Fs by investment manager, use the "Companies & Other Filers" search tool to enter a name. Alternatively, you can search for recently filed Form 13Fs by selecting "Latest Filings" and restricting your search with "13F" as the form type.
To learn more about Form 13F, visit the SEC's web site here and read answers to frequently asked questions here. Read this New York Times blog entry for an example of the information that can be discerned from the forms.