The largest and most expensive corporate proxy battle in history ended with a big question mark.

Procter & Gamble, citing preliminary voting counts, announced at the conclusion of the company’s annual shareholder meeting Tuesday that its slate of 11 directors had been elected.

Not so fast, said Nelson Peltz, the activist investor who had been seeking a seat on the company’s board through his investment firm Trian Fund Management. In an interview on CNBC shortly after the meeting was adjourned, Mr. Peltz said the vote was “as close to a dead heat as possible,” suggesting the totals were “plus or minus one percentage point.”

Mr. Peltz said the tallies he had seen from his proxy solicitor earlier in the morning showed that he was in the lead. In a news release put out shortly after the meeting ended, Mr. Peltz, whose firm owns $3.5 billion worth of Procter & Gamble stock, said he would await certified election results by the independent inspector of elections.

The bizarre outcome leaves unresolved whether Mr. Peltz will gain the board seat he sought in his effort to bring about change to a company whose share price has lagged that of its peers for a decade. But it is likely to continue the sometimes acrimonious debate over the strategy of the huge household products company, whose brands include names like Tide, Pampers and Gillette.