Activist investors like Elliott, Third Point and Trian have grown in stature and influence, taking on even stalwarts of the business world, including General Electric and Sony. And they have inspired traditional mutual fund managers — known for decades as reluctant to pick fights with company boards — to quietly back activists or pick fights of their own.

This steady drumbeat of activism eventually swept up Arconic. Once a part of Alcoa, the 129-year-old aluminum producer, the company was spun off last year to focus on the higher-margin business of producing parts for airplanes, cars and the oil and gas industry.

It quickly became a target for Elliott, founded by the billionaire Paul E. Singer and now one of the most successful activist shareholders around. The fight has become one of the most watched on Wall Street, rife with insults and innuendo and notable for the company’s insistence on battling in public rather than reaching a truce quietly behind the scenes.

Only days before Arconic shareholders are to gather in Purchase, N.Y., the company and Elliott, which controls some 13 percent of Arconic’s stock, have come to terms. Each side has claimed some measure of victory.

Under the terms of the settlement, Elliott will receive three of the four board seats that it had been seeking, with one of those directors being added to a committee searching for a new chief executive. Elliott will also have a say on the selection of the new chief, and its preferred candidate for the job, Larry Lawson, will be among those to be considered.