Some of L.A.'s richest manage to keep wealth secret.

We call them the ones who got away. They're the people whose net worth is believed to be at least $500 million - the floor for this year's wealthiest Angelenos - but whose actual wealth could not be determined. They're very very rich we just don't know how rich.

Take the Bings, the L.A. family whose fortune was made by Leo Bing, the late real estate developer. The Bing family foundation, headed by Leo's son Peter, has donated untold millions to USC, Stanford University, Harvard-Westlake School and other institutions.

But a knowledgeable Los Angeles lawyer said the family's real money is held by Anna Bing Arnold, who remarried after Leo Bing's death. Estimating her net worth is another matter.

"She would definitely qualify for your list, but don't waste your time. You'll never track her (wealth)," the lawyer said. "She's so private that even if you managed to get her personal attorney on the phone, he'd never admit it."

Some members of the old-money establishment are relatively accessible, like Caroline Ahmanson, whose family foundation alone has assets of more than $650 million. 'She and her late husband Howard Ahmanson, founder of Home Savings, did not have any children of their own, but Howard had a son from an earlier marriage, Howard Jr., who is married and has a son. Then there are a couple of nephews who have 11 kids between them 16 heirs in all.

So how much do those 16 stand to inherit? "We don't talk about that," Ahmanson says.

That none-of-your-business attitude is not limited to old-money types, either.

Plenty of nouveau fiche Angelenos are adept at keeping their net worth a mystery. One example is Leonard Green, founder and nameplate partner of Westside-based Leonard Green & Partners L.P.

Green has been involved in several huge deals, including the purchase of the Thrifty Corp. drugstore chain from Pacific Enterprises Inc. in 1994. Thrifty was merged with Payless Drug Stores Northwest Inc., and then Green sold the combined chains in 1997 for $2.5 billion. That deal alone is said to have netted Green more than $100 million - though no one is giving exact figures.

Last year, Green bought and combined Kmart Corp.'s Builders square home improvement chain with Hechinger Co., creating the nation's third-largest home improvement chain. Combined company sales in 1997:$4.6 billion. And just recently, Green raised $1 billion in equity for a new buyout fund, mostly from institutional investors, making Leonard Green & Partners the largest buyout shop in Southern California.

Several insiders believe Green would qualify for the list, but he's not talking and there is no way of accurately estimating his fortune.

An even lower-profile dealmaker is attorney and CPA Ralph J. Shapiro. whose net worth is several hundred million dollars. several sources said.

Shapiro, reached at his Beverly Hills office, insisted he is not among L.A.'s richest.

"I was born in Lithuania and came here with my immigrant father." he said. "My dad once said, 'What a country,' and I said. 'Pop, you're right. Where else can you go and get a free public education and succeed and help out.' I've been married to the same woman for 40 years, lived in the same house for 31 years, and if I get lucky, we'll either give away or spend our last dollar by the time we die."

Shapiro made his initial fortune by helping major corporations settle complex disputes the kinds of battles in which high-priced attorneys fought over hundreds of points of contention. Shapiro was known for quickly boiling the dispute down to four or five basic issues. That distillation in hand. the CEOs could send their expensive attorneys home and quickly resolve the dispute.

Shapiro earned top dollar for his services, but today he is content to manage his own investments. His portfolio has commercial real estate, much of it in Beverly Hills, and lots of diversified securities.

It was Shapiro's decision in recent years to give away some of his fortune that drew attention. "Until the last few years, we were very low profile," he said. "But I'm 67 years old, so we started to do things (for charity)."

Shapiro is a major donor to United Cerebral Palsy, United Way and UCLA, where a courtyard at the Law School is named in his honor.

The people most in the know about L.A. wealth tend to be high-end professionals personal attorneys, private bankers, money managers, estate planners and a few well-connected fund raisers. But most declined to help identify L.A.'s hidden wealthy, for two reasons.

First, discretion is a virtue more valued than gold in these ratified circles. And second, competition to represent the super-wealthy in a professional capacity is fierce. Those representing such clients are loath to reveal much of anything about them.

Which brings up one aspect of L.A. wealth that sets it apart from wealth in other cities.

"We're a meritocracy. Whether you have (wealth) or not, it's possible to move in here and advance in the community very fast," said John Argue, principal of the law firm Argue, Pearson, Harbison & Myers, who represents many wealthy clients.

So who does Argue represent?

He'd rather not say.

Contributing reporter Benjamin Mark Cole contributed to this story.