Over the last few years, several firms have tried to buy wireless operators in the US with varying degrees of success. We have seen mergers of US telecom firms blocked by courts while firms from outside the US have had more success moving into the US market, such as Sprint and Softbank. A French company called Iliad has made a bid for T-Mobile US and a result of that bid is that its stock price has dropped 13% in trading.
Iliad made a cash offer for T-Mobile US of $15 billion for 56.6% of the wireless firm. Iliad says that T-Mobile has a "disruptive position" in the US that is very similar to the position Iliad has in France.
Sprint parent company Softbank and T-Mobile have already reportedly agreed to broad terms for a deal that would see Softbank buy into T-Mobile. The Iliad deal may be easier for T-Mobile to pull off since it will have no red flags for regulators concerned about competition in the US market.