Independent News & Media said Irish businessman Denis O'Brien raised his stake in the company to 16.43 per cent.
The stake buy follows a similar increase announced earlier this week which lifted O'Brien's holdings in the Independent newspaper owner to 15.37 per cent.
O'Brien is viewed as a dissident shareholder by the board of Independent News and Media. Its chief executive Tony O'Reilly is the largest shareholder with a 26.5 per cent stake in the group.