Activist investor Elliott Investment Management on Monday sent a letter to the board of NRG Energy urging the U.S. utility to conduct a review of its home services strategy and add new independent directors.

The company's shares were up 7.14% premarket following the letter.

The recommendations will remedy NRG's underperformance and strategic missteps including the acquisition of Vivint Smart Home Inc, Elliott said.

In December, NRG said it would buy Vivint Smart Home Inc for $2.8 billion in cash.

The activist investor called it "the single worst deal in the power and utilities sector in the past decade".

Elliott manages funds that have an investment of about $1 billion, representing a more than 13% interest in NRG Energy.

(Reporting by Mrinalika Roy in Bengaluru; Editing by Arun Koyyur and Sriraj Kalluvila)