Think the MetroPCS merger with T-Mobile is a done deal? Think again.

Investment groups with an interest in MetroPCS are becoming increasingly vocal about their opposition to the deal. Their position is that a merger would saddle the new company with too much debt. Essentially, it’s a “reverse” merger, in which shareholders of a private company purchase stock in a newly formed shell company. This new company would be 74% owned by T-Mobile parent company Deutsche Telekom.

A reverse merger is a good option for a company that doesn’t need an immediate influx of revenue, and has a long-term growth strategy. MetroPCS is currently supporting the deal, saying it has “both immediate and long-term compelling economic value” for their investors.

In addition to owning a large stake in the new company, Deutsche Telekom would pay investors of MetroPCS a $1.5 billion lump payment, and loan $15 billion to the newly formed entity. With an interest rate of seven percent, that presents a lot of debt, and is centric to the argument against the merger. The current structure of the deal values the company at $7-8/share, and MetroPCS currently trades around $11.

Nobody else has come forward with an offer for MetroPCS, and the mobile carrier market is getting tighter every day. The rumored AT&T-Verizon deal to purchase Vodafone looms large, and T-Mobile lost around two million subscribers last year. T-Mobile and MetroPCS are the fourth and fifth carriers, respectively, so merging makes a lot of strategic sense. Investors, however, don’t think the numbers add up.