Groupe Bruxelles Lambert , the Belgian holding company controlled by the families of Albert Frere and Paul Desmarais, said on Wednesday it had slightly increased its stake in Lafarge. 
 
The AMF financial markets watchdog said it had received a letter in which GBL said it held 15.92 per cent of the capital and 15.01 per cent of the voting rights in the world’s biggest cement producer. 
 
On Dec. 11, GBL held 15.001 per cent of the capital and 14.13 per cent of the voting rights. Investors have to notify their stake when they break the 15 per cent level.