Sprint and T-Mobile are reportedly planning to jointly bid approximately $10 billion on spectrum in next year's FCC incentive auction.

The mobile heavyweights will form a joint venture in order to place bids in the auction, which will be offering up spectrum relinquished from TV broadcasters that no longer need it, according to the Wall Street Journal.

The $10 billion is part a $45 billion Softbank package meant to finance Sprint's rumored acquisition of T-Mobile, the paper said.

Reports of a Sprint, T-Mobile merger emerged late last year, and the firms reportedly agreed on terms early last month. A final announcement may come sometime this summer, if the Journal's anonymous sources are to be believed.

Sprint declined to comment on the reports, while T-Mobile did not immediately respond to PCMag's request for comment.

This joint venture will likely only happen if the merger deal is still in play, the Journal said. But going after spectrum together could help the carriers snap up spectrum that would otherwise be secured by AT&T and Verizon, which have more money to spread around.

Smaller carriers like Sprint and T-Mobile have been asking the FCC to impose restrictions on how much their larger rivals can purchase. AT&T was not a fan of that plan, and threatened to back out of the auction altogether if onerous rules were put in place.

The FCC is still working out how its incentive auction will work.

Any merger between Sprint and T-Mobile, meanwhile, will require the approval of the FCC and Department of Justice, which gave the idea a rather chilly reception in January.

Sprint appears to be bracing for what could be a lengthy regulatory review, according to Bloomberg, which suggested that the company's controlling shareholder SoftBank is requesting longer-than-usual financing commitments from lenders.

PCMag lead mobile analyst Sascha Segan outlined six reasons why a merger would be a bad idea—chief among them is the companies' incompatible networks. Segan also recently examined a map that illustrates the general overlap of both networks, explaining that a deal would do little to expand Sprint and T-Mobile coverage around the country.

However, a rejected merger could cost Sprint more than $1 billion in cash, which could hurt the already-strapped carrier.

For more, see Don't Believe Sprint's T-Mobile Merger Lies and Sprint and T-Mobile's Painful Technical Path.