Troubled Japanese tech giant Sony's president and CEO Howard Stringer is to step down, the firm said on Wednesday as it looks to staunch four years of losses in the face of fierce competition.

Sony has been assailed on multiple fronts, with mobile phones challenging its key games division – the scene of an embarrassing hacking scandal – huge losses in televisions, and piracy threatening its music and film assets.

Welsh-born American Stringer, 69, who was knighted in 1999 and was the first foreigner to lead the firm, is the latest in a series of high-profile outsiders to leave top positions in Japanese companies.