CNBC is reporting that Sprint and regional carrier MetroPCS were literally hours from announcing an $8 billion merger when Sprint's executive board rejected it — even after it had CEO Dan Hesse's sign-off.

The circumstances of the deal are unclear, but the two companies had apparently been hammering it out for "months," says CNBC's David Faber. Considering the complexity of Sprint's spectrum situation as it makes the transition to LTE, Clearwire's financial troubles, and LightSquared's woes, it stands to reason that the company would be looking at other alternatives. That said, much of MetroPCS's spectrum lies in the AWS band, which would've made integration considerably more difficult; Sprint doesn't currently use AWS.

MetroPCS just reported earnings this week and registered 9.35 million subscribers as of the end of Q4; combined with Sprint's 55 million, the new company would still fall well short of juggernauts AT&T and Verizon but likely would've put T-Mobile in an even more precarious and fragile position than it is today.

In regard to the rumored deal, Sprint says "we never comment on rumors or speculation."