Investors are set to revolt this week over Sir Martin Sorrell's £70m pay packet - up from £44m last year.
More institutional investors are lining up to oppose the WPP chief executive's remuneration than last year, when 22 per cent rejected the company's remuneration report, according to the Sunday Telegraph.
This year, the AGM takes place on Wednesday, and the deadline for voting is tomorrow.
Sorrell's pay is the largest of any public company chief executive in the UK; but this year, investors may decide that he's receiving too much.
Sorrell's pay package includes about £63m in shares, awarded under an incentive scheme from 2009 that was reformed after investor outrage in 2012, but remains in place. However, it seems unlikely that ad giant WPP will be humiliated by most of the investors opposing the remuneration report, an ordeal they had to face on 2012.
WPP chairman Roberto Quarta said in the company's recent annual report: "Sir Martin's public profile, as one of the world's most successful CEOs and leading commentator on global economic affairs, is of enormous material value to WPP, bringing prestige, talent and new business to the group."
Shareholder advisory group ShareSoc recommended its members to reject the remuneration package in May. ShareSoc said Sorrell's package is "far too high".
ShareSoc director Cliff Weight said: "In my view, it should be significantly less than half this amount - that would be much more reasonable and certainly more than adequate.
"In view of his share holdings and existing incentive awards, I don't see why he need to be given any more incentives. I don't think it will make him work any harder."
Shareholder group Pirc put forward similar advise, calling Sorrell's pay "excessive".
Pirc said: "The shares already held should provide him with substantial alignment with shareholders and incentive to perform. The issue for the company is not his retention, it is his succession and replacement."
Another challenge facing the company is who will replace Sorrell, 71, when he leaves as chief executive, having built WPP into one of the world's biggest advertising firms and becoming its most recognisable face.
In the annual report, Quarta said: "At some point we all leave our jobs. The question is when. Whether, in Sir Martin's case, that happens tomorrow, in one, two, three, four or five years, or even over a longer period, we have already begun to identify internal and external candidates who should be considered."