Cash-strapped Clearwire, which also counts Sprint as its biggest customer, has long been seen by analysts as an acquisition target for Sprint.
The company, which has been looking to raise more financing to upgrade its network and to keep the business afloat, has said that it could run out of money in the third quarter of 2013.
A planned purchase of 70 percent of Sprint by Japanese mobile firm Softbank (9984.T), with an associated capital infusion, would help Sprint finance a Clearwire buyout.
But some minority Clearwire shareholders -- including No. 2 shareholder Mount Kellet Capital Management LP and No. 4 Crest Financial Limited -- have expressed concerns over a deal with Sprint, suggesting that Clearwire should look at other options.
Between them, the two investment firms own nearly 15 percent of Clearwire's publicly traded shares and Sprint needs the approval of minority shareholders to proceed.
Crest and Mount Kellet did not immediately comment after the announcement.
On Tuesday, Crest Financial filed a lawsuit against the company and Sprint to try to thwart a deal.
Clearwire's other minority shareholders include Intel Corp (INTC.O) and Comcast Corp (CMCSA.O) who own around 12.4 percent between them. Sprint has been in discussions with those companies about purchasing their shares, according to people familiar with the matter.
Sprint, which is also Clearwire's biggest wholesale customer, had a 51.7 percent stake in Clearwire as of December 11.
The offer also needs the approval of Japanese mobile company Softbank Corp (9984.T) and is contingent on the planned sale of 70 percent of Sprint to Softbank, Sprint said in the regulatory filing.