T-Mobile US Inc. borrowed US$3 billion as the mobile carrier engages in an expensive battle to buy more 5G airwaves.

That was up from an original US$2 billion and came in three parts, maturing as late as 2031. The proceeds will be used for general corporate purposes, which may include financing acquisitions of additional spectrum and refinancing debt, according to a statement Monday.

Communications providers are amping up their bids in a 5G airwaves auction in the U.S., which may see T-Mobile’s peers such as Verizon Communications Inc. and AT&T Inc. tap the debt markets as well. The auction -- which still has several more rounds of bidding ahead -- has now surged past US$80 billion, well above analysts’ estimates of US$47 billion.

The frenzy underscores how crucial these midband frequencies are to companies trying to seize global leadership in emerging 5G technology. The airwaves are expected to drive a yearslong surge of profits when deployed for next-generation mobile devices, autonomous vehicles, health-care equipment and manufacturing facilities.

Deutsche Bank AG, Citigroup Inc., Credit Suisse Group AG, Goldman Sachs Group Inc., Barclays Plc, JPMorgan Chase & Co. and Morgan Stanley managed the bond sale, according to a person with knowledge of the matter, who asked not to be identified because the details are private.

T-Mobile shares closed the day down 1.6 per cent to US$132.93. They gained 72 per cent last year, compared with a loss of 4.3 per cent for Verizon and a 26 per cent skid for AT&T.

--With assistance from Gowri Gurumurthy.