NEW YORK ( TheStreet) -- When the government charged Goldman Sachs ( GS) with civil fraud on April 16, its stock plunged more than 15% not because of any potential fine, but because the investment bank's reputation was now on the line.

The shares tumbled again this past Friday following reports that a criminal probe of the firm's conduct is underway on top of the original accusation from the Securities and Exchange Commission that Goldman misled one client in favor of another and profited from the loser's misery.

From the time charges were announced through the end of last week, Goldman investors lost nearly $20 billion in market value.

Goldman has refuted the charges, and vowed to defend itself, its trader, and its reputation. But e-mail messages showed that, if nothing else, employees were celebrating in the misfortune of its prized clients. (The assets were called "crap pools" and "sh*tty" and the trader imagined himself as a silent oracle, dancing victoriously in a pile of subprime ruins.)

The notion that a Goldman representative could look an investor in the eye, rubber-stamp a deal, and imply that it supported both sides equally when it obviously didn't is problematic. This apparent disingenuousness, the profane language, and the high-profile disclosure of it all threatens to alienate clients and besmirch Goldman's brand. A downgrade of the stock on Monday was essentially based on this thesis.

And if there was any doubt, the severe hit in the stock price illustrates that investors believe the "Goldman Sachs" brand is the firm's most valuable asset - albeit its most intangible one. Goldman's clients, its people, its products and its investors all flock there for that name. But what is it worth? And how badly will the SEC's fraud allegation devalue it - if at all? What if criminal charges follow?

We asked some experts to find out, and put together a graphic showing components that make up a firm's reputation:
How Much Is Goldman Sachs Worth?

TheStreet.com: What's the name "Goldman Sachs" worth?

It's hard to define...

"It's like that judge that once said, 'I can't define pornography, but I know it when I see it.' When you think about Wall Street, you think about Goldman Sachs. I don't know how you put a value on that, but it's worth a lot." -- Matthew Tuttle, president and chief investment officer of Tuttle Wealth Management

...but incredibly valuable to the firm

"Take Lehman Brothers: The problem wasn't that Lehman was necessarily insolvent, but it was illiquid. Once the market believes a company has failed, perception becomes reality. Reputation is everything for Goldman Sachs. It's the no. 1 asset above everything else... The SEC case is kind of the ugliest bullet you can fire." -- Scott Colyer, CEO and CIO at Advisors Asset Management

...to regulators

"The Fed started to look at reputational risk as something a bank should hold capital against in mid-90s. It's a very hard thing to quantify. But the Fed threw it in there as a factor because they were looking at whatever risk could sink the bank, and clearly one of the top ones was reputation." -- Doug Landy, former counsel at the Federal Reserve Bank of New York, who now heads Allen & Overy's bank regulatory group

...and to the market.

"The only real valuation is their market cap. At the end of the day, it's all about their market cap." -- Jack Reutemann, founder and president of Research Financial Strategies

Still, if Goldman Sachs keeps earning money for clients and shareholders, "Goldman Sachs" may be worth the same as it was pre-SEC charges.

"The people who bank with Goldman are mostly insiders for whom the hubbub doesn't make much difference. And so it may not hurt their business as much as you might think. They're very knowledgeable; they've seen this before; they're interested mostly in the financials. You bank with Goldman, you know that they're sharp. So, I'm not sure it would make that much of difference." -- Paul Gary Wyckoff, director of Hamilton College's public policy center

-- Written by Lauren Tara LaCapra in New York.

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