T-Mobile late Monday announced it is kicking off a convertible offering in hopes of raising money for general corporate purposes. That includes capital investments and the purchase of more spectrum, which the carrier says is unrelated to any airwaves it may acquire in the FCC’s ongoing AWS-3 spectrum auction. 

T-Mobile is offering to the public 17,391,305 shares of its Mandatory Convertible Preferred Stock with a liquidation preference of $50 per share. The carrier also plans to give the underwriters the chance to buy up to 2,608,695 shares of its Mandatory Convertible Preferred Stock.

Goldman Sachs, Morgan Stanley and Citigroup will joint run the books for the offering. Barclays, Credit Suisse, Deutsche Bank and J.P. Morgan Securities LLC are co-managing the offering.

T-Mobile’s plan to raise spectrum capital comes as the AWS-3 auction appears to be winding down and topping out close to $42 billion. T-Mobile is an approved bidder in the auction but with the spectrum values so high and T-Mobile’s focus on securing low-band spectrum for its second LTE network, it’s possible T-Mobile has fallen out of the running for the 65 MHz of AWS-3 up for grabs.

T-Mobile stock in early Tuesday trading is down nearly five percent on a day when the other three U.S. Tier 1 carriers are also selling off. The stock slide is stemming from Verizon’s announcement that strong competition and promotions may produce short-term impacts on the carrier’s wireless earnings and margins.