Rupert Murdoch’s Fox and Netherlands-based Ziggo Sport — owned by John Malone’s Liberty Global and Vodafone — said they had been targeted in a European Commission investigation into a possible cartel in sports broadcasting rights.

The owner of UPC in Ireland, Liberty Global, has reported a decline in second-quarter revenue as its Dutch unit Ziggo lost customers, highlighting the difficulties for billionaire John Malone’s European cable company in its hunt for growth.