AT&T ends $39bn bid for T-Mobile USA
20 December 2011 Last updated at 23:18 GMT
It was meant to be the biggest deal of 2011. Germany's Deutsche Telekom agreed to sell its American mobile business, T-Mobile USA to AT&T.
But then the regulators stepped in concerned about the impact on competition and prices for consumer.
On Monday night the deal collapsed and the boss of the German telecoms company, Rene Obermann hit out at the regulators, saying it was incomprehensible to block the transaction.
Nigel Cassidy reports.