Sprint has taken steps to mitigate the risk that it could be called to pay Clearwire's debts if the financially struggling WiMAX operator, in which Sprint owns of 54 percent stake, defaulted on its loans.

Sprint reduced its Class B voting shares from 54 percent to 49.8 percent, according to SEC documents filed today. The move does not affect Sprint's other governance rights or financial holdings in Clearwire, which remain at 54 percent.

"By taking this action, Sprint is proactively providing protection and flexibility with respect to its debt agreements and eliminating ongoing investor concerns about any potential cross-default risk," said a Sprint spokesman.

A spokesman for Clearwire said it "enjoys a productive working relationship with Sprint." Sprint resells Clearwire's mobile broadband service under its own brand and is dependent on the WiMAX operator for its 4G strategy.

Investors have been concerned that Sprint would be held liable for Clearwire's debts if the company were to go belly up, since Sprint holds a controlling stake in Clearwire. By reducing its voting power to less than 50 percent, Sprint cuts the risk that it will have to pay out to Clearwire's debtors in the event the company goes into default.

Wells Fargo analyst Jennifer Fritzsche said Sprint's move was expected.

"With today's announcement, this removes any concern about a cross-default risk – which should allow Sprint to be able to be more opportunistic in the debt markets (and likely raise lower cost debt than it would have been able to otherwise with this issue still a factor)," Fritzsche wrote in a research note. "We note this is not a surprising move in our view."

Walter Piecyk at BTIG Research expressed a similar view.

"Last year we wrote about how Clearwire's debt could trigger a default for Sprint, because Clearwire could be considered a subsidiary of Sprint under certain debt agreements based on Sprint's 54 percent voting stake, even though Sprint did not consolidate Clearwire in its quarterly results," Piecyk wrote. "Today, Sprint resolved the issue of whether Clearwire could be considered a subsidiary by reducing its voting interest in Clearwire below 50 percent, while maintaining its equity stake in the company. This is not a sale of Clearwire's stock into the market."

Sprint's stock was down about 1 percent in morning trading on the New York Stock Exchange (NYSE), while Clearwire's stock rose slightly with a 3 percent gain.

Clearwire said in December that Sprint had the option to sell off some of its voting shares to reduce its financial risk "at any time to the extent Sprint determines in good faith such actions are reasonably necessary to eliminate or ameliorate any risk that a breach or default by Clearwire Corp. or any of its subsidiaries under their debt agreements could trigger a cross-default or cross-acceleration under Sprint's debt agreements."