Financiere Agache, a unit of luxury goods group billionaire Bernard Arnault, will buy up a 27% stake in Arnaud Lagardere's personal holding company LCM, Arnault and Lagardere said in a joint statement on Wednesday.

The partnership between Arnault and Lagardere comes as Lagardere looks to shore up his position amid pressure from activist fund Amber Capital and Vivendi billionaire Vincent Bollore.