Prudential boss Tidjane Thiam is struggling to make headway with skeptical investors who question the value of his $35.5 billion acquisition of AIA.

In a series of meetings with UK investors this week, the chief executive of the British insurer has been spelling out the merits of buying AIG's Asian unit ahead of a make-or-break vote on the deal on June 7.

Three quarters of Pru's investor base must back what amounts to a huge bet on Asian growth. Thiam is asking them for $21 billion in the biggest ever M&A-related rights issue.

But many shareholders remain unsure about the deal and the price that Prudential proposes to pay. Individual voting decisions appear balanced on a knife edge.

At the end of the day, it comes down to what you think of the overall transaction at this price, said one top-20 investor who met with Thiam this week.

There is no doubt that AIA could be a good business, but it's a question of whether this is the right price and we are not unequivocally convinced.

We have got to do some serious thinking about this.

It was a very open, constructive meeting, but have we learned a great deal more that we didn't know before? Probably not, he added.

Another top-20 investor who also met Thiam agreed that the price could be the deal-breaker.

The deal is a good one, but the price is too expensive - that's the problem, he said.

This roadshow has been better, but in these markets I still think they are going to struggle to get it through, he added.

LONG-TERM BET

From the start, Pru's ambitious move for AIA has struggled to win over the doubters.

But it was the UK Financial Services Authority's decision to force a tweak in its bid, and an unprecedented last-minute delay, that raised concerns over management's ability to execute such a mammoth deal.

It's just trying to separate out what's gone on in the short-term from maybe the long-term opportunity, said a third top-20 investor who met Thiam.

I found this meeting quite reassuring, but I'm still unsure. I wonder that if it does get voted down whether in time people will think that this was an opportunity that we passed over for short-term reasons, but was a great long-term story.

Toby Langley, an analyst at Bernstein Research, has little doubt where the focus should lie.

We believe investors able to identify the long-term drivers of growth in developing Asian life markets and ride out the medium-term dilution in earnings will be handsomely rewarded for doing so, he said in a note published on Wednesday.

The Asian growth story itself has detractors on the shareholder roster.

When Vodafone bought into India, there was great excitement because it was felt this was a nice long-term growth market, said another top investor.

But they have just had to write it down by $3 billion because actually despite the long-term growth prospects, the government's just allowed massive more competition. So the risks of the deals in developing markets is just not priced in.

Thiam, a former Ivory Coast government minister who joined Pru as finance director in 2007, has been at the helm for less than a year, although the AIA deal had been attempted before by previous incumbent Mark Tucker.

He met with London-based investors in the early part of week before flying off to meet the insurer's Scottish investors on Thursday.

The first investor said Thiam was true to form during the meetings -- upbeat about the deal and positive about AIA's growth prospects -- but said the charm offensive might be wearing thin.

He's very confident about the deal and I can see how that could irritate some people, he said.

(Editing by Joel Dimmock and David Cowell)

India United kingdom