Who are the Players in the Antivirus Industry?

Everyone in the United States has heard of the leading antivirus vendors Symantec, Mcafee, Computer Associates, and Trend Micro. These companies have market-leading presence in the United States.  Microsoft, as well, has plans become a key player in this market.  Microsoft acquired intellectual property and technology from GeCad software in 2003, a company based in Bucharest, Romania.  They also acquired Pelican Software, which had a behavior based security as well as Giant Company Software for spyware and Sybari Software, which manages virus, spam, and phishing filtering.