According to a report from OPSWAT (via Softpedia), the free Microsoft Security Essentials is the most used antivirus worldwide, in the second quarter of 2011 (March 23 to May 15).
Microsoft’s free antivirus offered to users of genuine Windows operating systems including Windows 7 RTM and SP1, has been found to run on no less than 10.66% of the 43,000 computers around the world covered by the OPSWAT’s Q2 Antivirus Market Share Report.
But when comparing vendor share, the situation looks a bit different:
“AVAST Software and AVG Technologies both top this quarter’s worldwide antivirus market with 12.37% each. AVAST shows a decrease from its leading 16.19% last quarter, which could be due to a shift in the percentage of data originating from various countries. Avira and Microsoft rank third and fourth with 12.29% and 11.24% of the market, respectively,” OPSWAT notes.
OPSWAT stresses that the growth is due to Microsoft's move to push the security solution through Windows Update.