NEW YORK (TheStreet) -- SunEdison (SUNE) stock closed down 12.78% to $1.98 on heavy volume in Monday's trading session, as David Tepper's Appaloosa Management will seek an expedited trial in its challenge to SunEdison's proposed acquisition of Vivint Solar (VSLR), Bloomberg reports.

Under the terms of the transaction, which Vivint shareholders approved last week, SunEdison's TerraForm Power (TERP) yieldco is supposed to buy 470 megawatts of Vivint's assets for $799 million.

Appaloosa Management owns a 9.5% stake in TerraForm Power, and has alleged that the deal would benefit SunEdison more than the yieldco. 

"Appaloosa believes that an expedited trial is in the best interests of TerraForm and its stockholders," Appaloosa Management told Bloomberg in an emailed statement. 

A Delaware-based judge last week denied the preliminary injunction filed by the hedge fund to block the deal, claiming Appaloosa Management "couldn't prove" that the terms of the merger would harm TerraForm Power shareholders.

Tepper told Real Money on Friday that he would decide how to proceed only after receiving the transcript of the ruling, Real Money's Carleton English reports today

He has since chosen to take the judge up on his offer to fast track the case, Bloomberg notes.

TerraForm Power shares closed up 11.32% today.

About 65.85 million shares of SunEdison were traded today, well above the company's average trading volume of roughly 32.43 million shares per day. 

Separately, TheStreet Ratings team rates the stock as a "sell" with a ratings score of D.

SunEdison's weaknesses include its generally high debt management risk, generally disappointing historical performance in the stock itself and feeble growth in its earnings per share.

You can view the full analysis from the report here: SUNE

TheStreet Ratings objectively rated this stock according to its "risk-adjusted" total return prospect over a 12-month investment horizon. Not based on the news in any given day, the rating may differ from Jim Cramer's view or that of this article's author. 

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