RiskMetrics has weighed in against Pru buying AIG’s AIA Asian assets, saying $35.5 billion is too much. The risk advisory firm joins a chorus of analysts chirping away from Singapore to London about problems with a deal that would pay off a huge chunk of AIG’s debt to Uncle Sam while transforming Pru into an Asian powerhouse.

Prudential holds a shareholders vote on June 7 to clear a $21 billion rights offer to fund the acquisition. One big issue is the price tag, which has drawn scrutiny given the fact that AIG has limited leverage to demand a big premium since it is selling the assets under duress. Pru’s ability to hit its projected revenue “synergies” from the deal are a big concern too.

CLSA Asia Pacific Markets, a broker not involved with deal, said in a report last week that a plan keeping both AIA and Pru brands intact and competing with each other will negate such gains. “It is already a challenge to retain agents, let alone target a dramatic increase in sales,” CLSA said.

The view of RiskMetrics, which itself was bought only a couple of months ago, could help to unravel a big deal just when the falling market looks set to start pulling the rug out from under the M&A market.