Cadbury yesterday said in a regulatory announcement that Peltz now holds just under 73 million shares, or 3.47 per cent, an increase from the 2.98 per cent stake he originally purchased in March.
The move has increased speculation over the future of Cadbury's US beverage division, the sale of which was announced in March.
Several companies have emerged as bidders for the drinks arm, including the US private equity giant Cerberus Capital Management.
The Times today reported that the bid is expected to fetch around £7.5m (€11.1m).
The Tata group, India's second largest private-sector conglomerate, is in talks with private equity funds Blackstone and Lion Capital in order to carry out a rival bid, the newspaper said.
India's Economic Times reported that Tata is not interested in the entire beverages portfolio, and will argue for the right to separate the Snapple brand.
Cadbury's drinks arm also includes leading soft drink brands such as Dr Pepper, 7UP, Hawaiian Punch and Clamato.
The Tata group's "financial exposure in the deal is estimated to be just over $2 billion", the paper said.
According to Forbes, US traded shares in the confectionery giant have now climbed 75 cents, or 1.4 per cent, to $53.96 in trading Thursday on the New York Stock Exchange.
The division of Cadbury's confectionery and beverage divisions could leave the chocolate business vulnerable to takeover, the publication speculated.
Jeremy Batstone, a Charles Stanley analyst, told Forbes that Peltz now wields a lot of power in the company.
"Peltz has clearly not gone away," he said.
"He's reminding the board that he's still there and still wielding his bicycle chain."
One possible bidder for the confectionery business could be US food group Kraft.
Last week Peltz bought a 3 per cent stake in Kraft Foods, and he will reportedly encourage Kraft to sell brands such as Post cereals and Maxwell House coffee in order to focus on improving its core frozen food and cheese businesses.