Updated from 3:09 p.m. EDT

The chairman of troubled U.S. health insurer

Aetna

(AET)

told shareholders on Friday that the company intended to remain independent but would consider serious acquisition proposals.

"Aetna is not for sale. We are not seeking offers," said William Donaldson at the Hartford-based company's annual shareholders meeting. "If there is a legitimate and compelling proposal brought to our attention, we will take a look at it."

His statement comes more than a

month after the Aetna board decided to split the company's health and financial services businesses into two independent publicly traded companies. At the same time, it decided to reject a joint takeover offer from

WellPoint Health Networks

(WLP)

and

ING America Insurance Holdings

, a subsidiary of investment bank

ING Barings

.

"Mr. Donaldson effectively closed the door on companies going on fishing expeditions," said Dave Shove, an analyst with

Prudential Securities

. "He is only interested in serious offers." Shove rates Aetna a strong buy and his firm has done no underwriting for the company.

Aetna could certainly entertain an earnest offer and proceed with the company's separation at the same time. Donaldson could either put off a split or go ahead with a split if the offers are not very appealing. "If he entertained a 'legitimate and compelling' offer, Donaldson would not let the timing of a split affect his consideration one way or the other," Shove said.

"In the long run, the company will end up being split up, but whether those separate entities are under current or new management remains to be seen," Shove added.

ING is rumored to still be interested in bidding for part of Aetna. However, when asked for comment, Lilly Ackley, a spokeswoman for

ING America Insurance Holdings

, said only, "We have nothing to report at this time."

Meanwhile, in early March,

Southeastern Asset Management

disclosed that it had

amassed a 6% stake in Aetna and hinted that it might be involved with an acquisition proposal for the company. In a filing with the

Securities and Exchange Commission

, Southeastern said it had held "conversations with third parties" about "proposed corporate transactions of a significant nature."

Mason Hawkins, chairman of the board and chief executive of Southeastern, said the firm had a policy of not commenting on its investment positions. However, he did confirm that Southeastern has not filed anything further with the SEC with regards to ownership of Aetna.

Aetna has suffered from a plunging stock price that

forced chief executive Richard Huber to resign. He was replaced at the end of February by Donaldson, a board member of the company since 1977 and the co-founder of investment bank

Donaldson Lufkin & Jenrette

.

Shares of Aetna closed down 2 1/16, or 3%, to 57 7/8.