Microsoft has announced its intention to acquire a Romanian anti-virus firm called GeCAD Software to develop a Microsoft Anti-Virus offering.

Microsoft has been a target for malicious code writers with Windows being a favourite. Microsoft shares rose on the announcement whilst Symantec and Network Associates shares fell. Both Symantec and NA write security software including anti virus.

A spokesman for anti-virus firm Sophos said it could encourage the virus writing community to write viruses to subvert their code and reminded people that Microsoft's previous anti-virus offering flopped.