AT&T must be pretty sure that its much-criticized proposed merger with T-Mobile will go through, because if regulators block the deal it will be out $6 billion.

Reuters cites unnamed sources who say AT&T is on the hook to give T-Mobile parent Deutsche Telekom the hefty sum if feds block it from purchasing T-Mobile for $39 billion. AT&T would pay up with $3 billion in cash, $2 billion in spectrum and another billion in the form of a roaming agreement.

The FCC and Department of Justice must approve the merger for it to go through.

AT&T,T-Mobile USA break-up is $6 billion: sources [Reuters]

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