There are many sources for Securities & Exchange Commission (SEC) filings in subscription databases and free sources. Only a selected few are listed below. If you want to understand the difference SEC filings, the SEC has created a document to help. Of particular interest when it comes to Mergers & Acquisitions External are the 8-K, 14-C, 425, and Proxy Solicitation Materials i.e. 14-A.
This section contains basic information on laws and and information and sources of filings that will come up for anyone doing research in this area.
Additional information about laws governing the securities industry other than those below, can be obtained from the following websites:
First try the Investor Relations area of a public company's website frequently includes SEC filings. Beyond that, there are free sources for filings as well a subscription sources for filings prior to 1994.
There are subscription databases that may allow users mor sophisticated search and download options.
The Library does have filings though the following databases though searching within filings and across the database is limited. The subscription resources marked with a padlock are available to researchers on-site at the Library of Congress. If you are unable to visit the Library, you may be able to access these resources through your local public or academic library.