The embattled H.J. Heinz Co.'s courting of its biggest shareholders took a new turn yesterday when the Pittsburgh ketchup company promised to add two positions to its 12-member board and to make changes meant to give investors a bigger say in the company's affairs.

Heinz stopped short of trying to appease its most vocal critics, a dissident group of investors that owns 5.5 percent of its shares and is waging a proxy fight for five board seats. The Trian Group's nominees, including billionaire Nelson Peltz and golfer Greg Norman, do not meet the company's high standards for independent directors, a company spokesman said.

Heinz's announcement at an investor forum comes as the two sides have been trading increasingly nasty barbs over each other's management skills, intentions and tactics. Voting by shareholders has begun, but the final tally won't be complete until the Heinz annual meeting Aug. 16.

Trian quickly issued a statement taking credit for Heinz's "newfound willingness to add two new directors." It also said its meetings with shareholders have found widespread interest in near-term board changes.

Whether Heinz's overtures will be enough to swing institutional investors to management's side isn't clear.

Even the investor that the company was responding to most directly -- the California Public Employee Retirement System, or Calpers -- made no promises on how it would vote its 2.5 million shares, though it called the moves a good first step.

"We will continue to monitor the actions at Heinz and are evaluating the merits of all proxy filings, and look forward to a continued dialogue with the directors at Heinz," Fred Buenrostro, Calpers chief executive officer, said in an e-mailed statement.

He noted Calpers has a few other things it would like to talk to Heinz about, including a comprehensive plan that sets specific goals for improving operations and a discussion with the board committee that makes executive pay decisions.

Calpers' holdings pale beside the dissident group's 18.245 million shares or those of the company's largest stockholder, Capital Research and Management Co., of Los Angeles, which regulatory filings show owns more than 45.7 million shares of common stock. Capital Research manages the American Funds.

But the changes suggested by the influential California retirement system may please other institutional investors, who together control at least 70 percent of the company's stock. Heinz spokesman Michael Mullen said the company, which employs about 1,200 locally, had taken the action after meeting and listening to many shareholders.

Specifically, Heinz said it would change from a system that elects directors by plurality, or simply those with more votes than other candidates, to one that requires those elected to win a majority of shareholder votes.

It also will recommend allowing amendments to its bylaws to be approved with 60 percent of the vote rather than 80 percent, and to quickly seek shareholder approval if it adopts a plan to block hostile takeovers. It also will commit to meeting regularly with key shareholders and adding two more independent board members.

Chairman William Johnson is the only Heinz employee on the existing 12-member board.

Heinz said it is open to suggestions from shareholders on who the new board members should be. Calpers would like to see new directors with packaged food backgrounds and international marketing experience.

Mr. Mullen said there is no specific time frame on naming new directors, although the goal would be to find qualified candidates as soon as possible.

Both Trian and Heinz have offered packages of cost cutting and share repurchases in recent weeks with the challengers more willing to cut deeper and take on new debt than the company.

Observers have said in recent weeks that the company might need to do more to ensure the support of institutional shareholders. Even if they supported the company's strategy of trimming its portfolio to core products over the past few years, they cannot be pleased with the performance of the stock, which fell 14 percent last year alone.