(Bloomberg) -- A pair of activist investors agitating for changes at TransAlta Corp. have terminated their partnership ahead of the power company’s annual general meeting slated for Friday.

Mangrove Partners and an entity controlled by C. John Wilder’s Bluescape Energy Partners said in a regulatory filing late Friday that they would terminate their cooperation agreement.

The pair, which collectively owned 10.1 percent of TransAlta, had said they were prepared to launch a proxy fight at the company to replace five directors on the board. They also tried unsuccessfully to have regulators review a C$750 million ($560 million) investment by Brookfield Asset Management Inc. in TransAlta to determine whether additional disclosure and second vote on the investment should be required, among other matters.

It would be challenging for either investor to push ahead with their proxy fight at the meeting after the pair failed to file proper paperwork with regulators to pursue the challenge. They didn’t say in the filing whether they had abandoned their fight.

Mangrove President Nathaniel August threatened earlier this month to call an a special shareholder vote after the annual meeting if TransAlta failed to meet its demands on additional disclosure around the Brookfield deal and a separate vote on the matter.

It’s unclear whether Mangrove, which owns 7.1 percent of TransAlta on its own, will push ahead with those efforts after the AGM Friday.

A representative for Mangrove declined to comment. A representative for TransAlta and Bluescape weren’t immediately available for comment.

To contact the reporter on this story: Scott Deveau in New York at sdeveau2@bloomberg.net

To contact the editors responsible for this story: Elizabeth Fournier at efournier5@bloomberg.net, James Ludden

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