It was only a couple of weeks ago that shareholder discontent forced T-Mobile's parent company to sweeten its MetroPCS (NASDAQ:TMUS) buyout offer. Two hedge funds, Paulson & Co. and P. Schoenfeld Asset Management, so badgered MetroPC with SEC filings opposing the merger that Deutsche Telekom finally came up with terms that quelled the misgivings of those influential investors.

Now, Sprint Nextel's (NYSE:S) proposed buyout of its networking partner Clearwire (UNKNOWN:UNKNOWN) is also facing serious shareholder opposition.

Clearwire investor Mount Kellett Capital Management, which owns 7.7% of Clearwire shares, sent a letter to Clearwire's board soon after the Sprint deal was proposed in October, saying it believed "Clearwire's stock to be substantially undervalued."

Last December, another Clearwire shareholder, Crest Financial, holder of 5.2% of Clearwire shares, went further than just sending a letter. It sued the board, the company, and Sprint to stop the buyout. Crest alleged (link opens PDF) "breaches of fiduciary duty by Clearwire's controlling stockholders and its officers and directors."

Just this past week, an additional lawsuit landed on Clearwire's doorstep, this one from another shareholder, hedge fund Aurelius Capital Management. In its court filing, Aurelius said that Sprint, as Clearwire's majority stockholder, had forced "manifestly unfair" conditions upon the company's minority shareholders.

On April 9, Aurelius chairman Mark Brodsky wrote to the Clearwire board offering the company some financing to make it less dependent on Sprint. Brodsky wrote that though the $80 million it was willing to lend Clearwire wasn't even close to the $480 million available from Sprint, "We believe the $400 million differential could readily be obtained through a combination of the $240 million of financing proposed by Crest Financial Limited ... [and there would be] an additional $160 million ... we trust others would welcome providing."

Why the rush forward to provide Clearwire with funding? You can bet it's for the large cache of spectrum licenses Clearwire controls. DISH Network (NASDAQ:DISH) has already made a $2.2 billion offer to buy 24% of Clearwire's spectrum, and Verizon has offered to buy between $1 billion and $1.5 billion for a portion of spectrum.

The $2.1 billion that Sprint has offered for total ownership of Clearwire -- and all its spectrum -- just isn't cutting it now for those investors with a lot of shares at stake.

Seeing how successful P. Schoenfeld Management's proxy campaign was in defeating Deutsche Telekom's initial offer, Crest Financial has filed a preliminary statement informing the SEC it intends to "wage a campaign to convince the Clearwire stockholders to vote against the proposed merger."

If that's not enough of a headache, Sprint is now also facing its own hostile takeover attempt from DISH Network, which made a $25.5 billion counteroffer to Japanese telecom SoftBank's $20 billion bid.

Sprint taking total control of Clearwire may have originally been thought of as a done deal, but if there's anything certain about it, it's that nothing is certain.

Fool contributor Dan Radovsky has no position in any stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.