UPDATE 2-Top Cadbury investor would consider 820p bid

* Kraft bid at 820p "certainly stacks up"-top ten investor

* Independent Cadbury would find its targets "challenging"

* Cadbury shares close off 1.3 percent at 789p

* Kraft bid value 8.6 percent below Cadbury price

(Adds further analyst comments, background, shares)

By Raji Menon and David Jones

LONDON, Oct 22 (Reuters) - One of Cadbury's (CBRY.L) ten biggest investors said on Thursday a raised bid of 820 pence or 11.3 billion pounds ($18.7 billion) from suitor Kraft (KFT.N) "certainly stacks up" and would be examined very closely.

The London-based confectionery group issued upbeat third-quarter trading on Wednesday but the lacklustre reaction of Cadbury shares suggested Kraft may only have to offer a bit more than the current share price to win. [ID:nLK594844]

"If you believe the synergy numbers, then a figure of 820p certainly stacks up. And we would certainly look at that," the investor, who declined to be named, told Reuters.

The investor also said it would be "challenging" for Cadbury to meet its sales and profit margin targets, which it pushed up in Wednesday's update, if the group were to remain independent.

"Kraft may choose to wait until after its Q3's on Nov. 3 to formalise a new bid. We think patience will be rewarded," said analyst Warren Ackerman at brokers Evolution Securities.

"We think Irene Rosenfeld's credibility as Kraft CEO is at risk if the deal doesn't go through given that it has been played out so publically," he added.

Cadbury shares hit a new high of 808.95p on Wednesday, well above Kraft's cash-and-shares offer worth currently about 722p, but they then have drifted back and closed off 1.3 percent at 789p due to the likely absence of a counter bidder.

Cadbury has repeatedly rejected Kraft's 10.2 billion pound cash-and-shares proposal made in early September and the UK Takeover Panel has given the U.S. food group a deadline of Nov. 9 to come up with a firm bid or walk away for six months.

The investor appeared to agree with JP Morgan analyst Pablo Zuanic who believes that a deal with Kraft "may be closed near or at 820p" with a much larger cash component than the 40 percent cash initially offered by Kraft.

"That just tells you the bid will be between 820 and 850p. it gives you the number," said another investor, based in New York, who holds both Kraft and Cadbury shares.

Kraft's takeover proposal valued Cadbury's shares initially at 745p or 10.2 billion pounds but the fall in Kraft share has made it worth less as it ponders launching a higher firm offer for the maker of Dairy Milk chocolate and Trident gum.

At 1600 GMT, the Kraft bid value was 8.6 percent below the Cadbury share price <EU/MERGER1>.

"I do think the deal is going to get done. If not, the share price would have been an awful lot lower than where it is now. Strategically, Cadbury can carry on its own but it wouldn't be at this price without Kraft's proposal," said another Cadbury shareholder.

Speculation of a counter bid for Cadbury by a combination of Nestle (NESN.VX) and Hershey (HSY.N) appeared to fade. Hershey reported results on Thursday but made no mention of Cadbury while the Swiss food giant appeared to be more interested in share buybacks than big acquisitions [ID:nLM518486].

Evolution's Ackermann said Kraft's original bid at 745p valued Cadbury at 13 times its historic EBITDA earnings.

If put at the same 15 times multiple on which food deals over the last couple of year have averaged Cadbury would have a value of 850p per share. (Additional reporting by Victoria Howley) (Editing by David Holmes/Marcel Michelson)