NEW YORK (Reuters) - A phantom account scandal at Wells Fargo & Co has put the U.S. bank’s disclosure policies under a harsh spotlight.

Despite press reports that a federal regulator and the Los Angeles prosecutor were investigating sales practices at retail branches of the San Francisco-based lender, the bank, which agreed to a $190 million settlement, gave investors no indication of the scale of the problem.

The surprise spooked investors and has lopped roughly $19 billion off its market value since the probe disclosed last week that Wells employees had created roughly 2 million accounts for customers without their knowledge in order to meet internal sales targets. The bank has fired 5,300 people over the scandal.

While the settlement barely makes a dent in the $23 billion of profit the bank earned last year, the scandal’s aftermath has caused a 7.5 percent drop in Wells’ stock compared with a roughly 2.4 percent decline for the Dow Jones US Banks Index.

Investors, analysts and legal experts who spoke to Reuters said Wells Fargo’ silence did not mean it had broken the law. But there is broad agreement that it made matters worse by not being more forthcoming with Chief Executive John Stumpf under pressure to explain why this happened on his watch.

“Look, they’re lawyered up to the sky. They did the minimum legally required. Do I think that that’s fair to investors or that that’s all that investors need to know or want to know? No I do not,” said Nell Minow, vice chair of ValueEdge advisors, a corporate governance advisory firm.

“It further diminishes their already significantly diminished credibility in terms of their willingness to be transparent.”

Activist investors began filing shareholder resolutions with Wells Fargo on Thursday calling on the bank to split the roles of chairman and CEO, both held by Stumpf, in light of the recent scandal.

In another, activist investor Bart Naylor, a financial policy analyst for consumer advocacy group Public Citizen, said he has filed a shareholder resolution calling on the bank to study breaking up its business in the wake of the scandal.

Naylor, who has submitted similar measures at other large banks in recent years, called on Wells Fargo’s directors to study “whether the divestiture of all non-core banking business segments would enhance shareholder value.”

Meanwhile, Stumpf will testify before the Senate Banking Committee next week and U.S. prosecutors have begun an investigation into the bank’s sales practices.

“It is a scandal of almost unimaginable proportions,” former U.S. Securities and Exchange Commission Chairman Arthur Levitt told Reuters this week. “You cannot hold management immune from its consequences.”

MATERIAL OR NOT?

The tactics deployed in its branches were not a surprise for Wells. The bank had been looking into them since 2011, when it started firing employees over “inappropriate sales conduct.” A Los Angeles Times investigation published in 2013 described a “pressure-cooker sales culture” at the bank.

No mention is made of the bank’s internal probe, or authorities’ probes in the “legal actions” section of its latest quarterly or annual securities filings. The bank also did not say until this week that during the second quarter it had set aside money for the settlement.

Stumpf has since apologized and said management takes responsibility for what happened. Spokesman Mark Folk said the bank did not believe it had to disclose information to investors ahead of the settlement.

“Each quarter, we consider all available relevant and appropriate facts and circumstances in determining whether a litigation matter is material and disclosed in our public filings,” he said. “Based on that review, we determined that the matter was not material.”

The logo on a Wells Fargo bank building is seen in downtown San Diego, California March 18, 2014. REUTERS/Mike Blake

U.S. securities laws enforced by the SEC require public companies to publicly disclose meaningful financial and other information to investors. If something is “material,” it needs to be disclosed, but there is some subjectivity involved in defining what is material.

An SEC spokeswoman declined to comment on Wells Fargo. The bank’s auditor, KPMG, said it could not comment because of confidentiality requirements.

GET CONTROL

SEC rules prioritize the accuracy of information over the speed of disclosure, experts said. If management is unsure of the scale of a problem, it might delay releasing information in the interest of getting it right.

But companies also risk making a bad situation worse if they minimize problems that come to light.

JPMorgan Chase CEO Jamie Dimon famously referred to its so-called “London Whale” losses as a “tempest in a teapot,” just a month before disclosing it had lost more than $2 billion on the trades. Dimon later apologized.

Experts said Wells Fargo would have been wise to at least flag the issue earlier.

“They should have tried to get control over the release of the news, so that it wasn’t a bombshell that went off on someone else’s schedule.” Said Erik Gordon, a University of Michigan business professor

“Now they’re in the terrible position of looking like they did something and hid it.”