Prudential shareholders head to the ballot box next week to vote on a record-breaking $US35.5 billion ($41.7 billion) play for AIG’s Asian unit. However, a union of the two is far from assured.

Prudential Chairman Harvey McGrath has attempted to quell fears the acquisition of AIA is in jeopardy after voting adviser RiskMetrics advised clients to reject the deal.

RiskMetrics’ concerns about the premium paid for AIA have been compounded by conjecture over the tenure of AIA CEO Mark Wilson. The Financial Times reported last week he would quit the company should the merger proceed.

Speculation over Mr Wilson’s future has raised questions if other members of AIA’s executive team would join a post-acquisition exodus.

Prudential requires 75% approval from shareholders for the deal to pass. Mr McGrath says the “vast majority” of Prudential shareholders support the deal.

“I’m confident the combination of the two businesses will be a great success,” he said.

Should the June 7 vote pass, Prudential will emerge as the world’s largest non-Chinese insurer, the largest insurer in southeast Asia and the largest foreign insurer in China and India.

AIA will account for more than 60% of Prudential’s future profits.

Prudential has launched joint listings in Hong Kong and Singapore, keeping its primary listing on the London’s FTSE exchange.

Last week Prudential unveiled a record £14.5 billion ($25.05 billion) rights issue to fund its takeover of AIA, but the future of the division’s Australian and NZ assets remains unclear.

These assets are given scant mention in an investor presentation on the acquisition, with Prudential focusing instead on the growth potential in AIA’s key markets of Hong Kong, Singapore, Thailand, Malaysia, China and Korea.