Shares in French telecom company Iliad plunged by nearly 13.0 percent in early trading on Friday, pulling down the entire telecom sector after the company bid for US firm T-Mobile.
The price of shares in the company, which owns French low-price operator Free, were down 12.74 percent to 179.75 euros in an overall French market down 0.44 percent.
Shares in other French operators fell sharply.
Shares in Bouygues, which has a telecom arm, fell by 6.57 percent to 27.59 euros, in Orange by 2.94 percent to 11,41 euros, and in Numericable by 2.88 percent to 40.11 euros.
Late on Thursday, Iliad revealed it was bidding $15 billion (11.2 billion euros) for 56.6 percent of T-Mobile, controlled by German company Deutsche Telekom.
Its move offered T-Mobile, the fourth-biggest US wireless group, an alternative to a potential tie-up with rival Sprint.
The offer was described as 42 percent above what T-Mobile's price had been before reports of a potential Sprint tie-up began circulating.
Iliad is controlled by self-made tycoon Xavier Niel. Its subsidiary Free has thrown the French telecoms market into turmoil since emerging as a national cut-price operator, largely thanks to a capacity deal with French giant Orange.
Date created : 2014-08-01