How much can Arthur Andersen pay to settle claims that it botched the audit of collapsed energy trader Enron Corp.? 

A lot more than it is offering, Enron shareholders believe, eying a settlement of up to $4 billion. 

"$750 million is too small, or we would have settled, wouldn't we?" said a spokesman at one of the major investors suing Enron and Andersen. 

Andersen reportedly offered that amount to Enron shareholders, creditors and employees, who are gunning for cash from the firm in a welter of lawsuits, saying Andersen contributed to Enron's downfall. 

The plaintiffs are looking to Andersen's deep pockets for compensation as Enron offers little prospect of making up for the billions of dollars it lost. 

"You would expect somebody to low-ball you, straight out of the gate," the spokesman said. "The general presumption is that they can pay a good bit more than they have put on the table." 

The difficulty for plaintiffs is working out how much Andersen can pay without going bust. Rough estimates go up to about $4 billion. 

For starters, Andersen has about $300 million to $500 million in insurance, industry insiders say, drawing on a mixture of outside liability insurers and a string of "captive" insurance vehicles it owns, or partly owns, in Bermuda and other offshore havens. That would be part of a $1 billion plus "war chest" set aside to settle legal cases. 

On top of that, Andersen has about $1.2 billion from its divorce from erstwhile consulting unit Accenture , after a settlement in August 2000. 

Then there is cash amassed from the firm's $9 billion or so annual revenues, plus the equity of Andersen's partners in the firm -- the last level of wealth that might be tapped. 

About 20 percent to 25 percent of annual revenues might go toward a suitable settlement, one Enron shareholder told Reuters, putting the total at $2 billion or more. 

Insurers may already have figured that out and thrown in the towel. 

Any settlement would usually involve the firm's outside insurers, but with their limits smashed, they may already have cut checks and walked away, avoiding further legal costs, according to Rickard Jorgensen, a specialist liability insurance agent in Maywood, New Jersey. 

Andersen's outside insurers, thought to include Lloyd's of London insurance market [LOL.UL] and 15 or so U.S. carriers, have not said anything publicly about settlement talks.