Procter & Gamble Co (PG.N) said activist hedge fund manager Nelson Peltz had lost his fight to win a seat on the company's board, according to a preliminary tally of shareholder votes on Tuesday in the biggest-ever proxy fight.

Trian Fund Management LP CEO Peltz refused to concede defeat, saying the vote had been too close to call and that the company would await the certified results.

Sources said the difference in for and against votes for Peltz's board director nomination was within one percentage point.

But if the outcome is confirmed, it would be a bruising loss for Peltz, given that P&G sought to turn the proxy contest into a referendum on his credentials as a seasoned executive in the consumer sector with board director experience at Kraft Heinz Co (KHC.O) and Mondelez International Inc (MDLZ.O).

Peltz had called for the maker of Pampers diapers, Gillette razors and Tide laundry detergent to reorganize into three business units: beauty, grooming and healthcare; fabric and home care and baby, feminine and family care.

P&G, led by Chief Executive David Taylor, countered that management is already working on several operational changes, and that Peltz does not have the relevant experience to be helpful in the process.

Peltz was widely seen as the favorite to win the contest, because he had the backing of all three top shareholder advisory firms, which recommend how mutual funds should cast their vote, and was only seeking one board seat on P&G's 11-member board.

"Win or lose, Nelson Peltz has taken the activist campaign to the largest companies, which have previously been able to inoculate themselves from these kind of experiences by spending enough money to keep activists at bay," said Bruce Goldfarb, founder of Okapi Partners, which advises on proxy contests.

Trian, a US$14 billion New York-based hedge fund, owns a US$3.5 billion stake in the P&G, which also makes Crest toothpaste and Charmin toilet paper.

P&G, with a market value of about US$230 billion and more than 2.5 billion shares outstanding, represents the biggest and most expensive proxy contest on record.

The two sides collectively spent more than an estimated US$100 million on mailings, phone calls and advertisements to woo investors.

Vanguard Group Inc, State Street Global Advisors and BlackRock Inc (BLK.N) are P&G's top three shareholders. Individual stock owners, such as retirees and amateur stock pickers, collectively hold about 40 per cent of the company's stock, a much higher proportion than at most big companies.

P&G's large retail base is due, in part, to long-running stock-based incentive plans for employees and the attraction of its well-known brand names for "mom and pop" investors.

This is only the third time Trian has waged a proxy contest in its 12-year history. Two years ago it narrowly lost a fight with DuPont, although within a year the company's CEO was out a job and a faster cost cutting was underway.