DENIS O'Brien raised his stake in Independent News & Media (INM) to 29.9pc yesterday, the largest stake the billionaire businessman can own without triggering an automatic bid for the entire company.
Mr O'Brien bought a 5pc stake on Thursday and a further 2.9pc stake yesterday from South African-based investment company Investec.
Shares in INM, which owns the Irish Independent as well as around 200 titles in Australia, New Zealand and South Africa, slipped 2.6 cent, or 8.2pc, to 29.1 cents by the close of trading in Dublin yesterday. That pared gains so far this year to 42pc.
An investor can acquire up to 29.9pc of a company quoted on the Irish stock exchange.
If an investor passes this threshold, he must make an offer for the remaining shares, unless he receives a waiver from the Irish Takeover Panel.
The news was revealed in a stock exchange filing. Spokesmen for Mr O'Brien and INM declined to comment on the matter.
A spokesman for Communications Minister Pat Rabbitte said: "The Government's position remains that there must be plurality in the media -- of content and ownership."
The shares bought this week were acquired through Bloxham Stockbrokers in Dublin, which has previously acted for Mr O'Brien.
The latest moves come just five weeks before INM holds its annual general meeting.