Tanker operator Frontline, now based in Bermuda, started life as Frontline AB in 1985, and was listed on the Stockholm Stock Exchange from 1989 to 1997. In 1996 Norwegian shipping magnate John Fredriksen, through his company Hemen Holdings, acquired a controlling stake in Frontline. The company's operations were relocated to Bermuda in 1997, and it was listed on the Oslo Stock Exchange. Since b…