In a shock announcement, the SNB said on Thursday it would abandon the 1.20 per euro cap on the franc, causing market turmoil.

Holcim declined to comment on the SNB's move or its share price but said it planned to press ahead with the merger.

"Regarding a possible impact on the combination with Lafarge, what we can say is that we remain committed to the merger," Holcim spokesman Eike-Christian Meuter said.

A spokesman for Lafarge said the French firm also remains committed to the merger project.

Holcim shares closed 11 percent lower at 63.70 francs, after falling as much as 21 percent to 56.50. Lafarge shares closed 2.42 percent higher.

(Reporting by Caroline Copley and Gilles Guillaume; editing by Jason Neely and Geert De Clercq)

Stocks treated in this article : LAFARGE, Holcim Ltd