Arconic  (ARNC - Get Report) on Monday said it's CEO Klaus Kleinfeld (pictured) resigned the post amidst a brutal struggle with activist investing group Elliott Management and its relentless chief Paul Singer.

Arconic, a spinoff of aluminum giant Alcoa (AA - Get Report) that specializes in aerospace components, named director David Hess as interim CEO.

Arconic shares rose 9% after the news and changed hands at $28.22 in early trading Monday.

Arconic is a holding in Jim Cramer's Action Alerts PLUS Charitable Trust Portfolio. Want to be alerted before Cramer buys or sells ARNC? Learn more now.

Following the news, The Street's Jim Cramer, who manages Action Alerts PLUS Charitable Trust Portfolio, told readers that the trust sold another 300 shares of Arconic at roughly $26.75 per share. Following the trade, ARNC will represent roughly 2.38% of the portfolio, he said.

"Following our trade from earlier this morning (see here), we are booking profits on another portion of our Arconic position as Elliott Management has since announced that it intends to continue to fight for board seats at the upcoming shareholder vote in May," Cramer said.

Most recently, Elliott, last week urged shareholders to back its four dissident director candidates up for election at Arconic and to ignore the company's recently installed so-called "poison put" mechanism, which requires $500 million of liabilities to come due upon a change in control.

At issue is one of the most heated director-election battles of 2017, set to come up for a vote on May 16. Elliott Management's Paul Singer is hoping that shareholders back the fund's four dissident director candidates as part of a broader campaign to replace Arconic's chief executive, Klaus Kleinfeld, with the fund's CEO candidate.

The battle is especially contentious because the dispute over who should run the company means that a settlement in advance of the director election contest is unlikely. Elliott is only seeking to elect four dissident directors on the company's 13-person board. However, in a 2016 settlement, Alcoa agreed to add three of Elliott-nominated dissident directors to its board. Those three directors moved over to Arconic when it split from Alcoa in a transaction concluded in November.

"In terms of the proxy fight, we are leaning toward voting in favor of Elliott Management as this recent development highlights the need for a new direction at the company, but we will continue to evaluate all of the news back and forth between now and the shareholder meeting in May," Cramer said.