Shares in emerging markets specialist Standard Chartered Bank slumped Tuesday after U.S. regulators charged that it hid $250-billion in deals with Iranian banks in violation of U.S. sanctions.
The charges – strongly rejected – are the latest in a series of damaging scandals to hit London's global financial centre where light-touch regulation was hailed as a major benefit of the 1980s 'Big Bang' market deregulation.
Standard Chartered shares tumbled nearly 24 per cent in London late-morning trade after losing nearly 15 per cent in Hong Kong.
"Bad news for banks once again as the daggers are out for Standard Chartered with US regulators flexing their muscles," said Capital Spreads boss Simon Denham.
"The stock is being absolutely smashed this morning ... as investors fear that they might have actually been doing something illegal for years."
The U.S. Department of Financial Services said Standard Chartered systematically disguised foreign exchange deals with Iran that potentially opened the U.S. banking system to terrorists and criminals.
For its part, Standard Chartered said it "strongly rejects ... the portrayal of facts as set out" by the DFS.
"The group does not believe the order issued by the DFS presents a full and accurate picture of the facts," group secretary Annemarie Durbin said in a statement to the Hong Kong stock exchange.
Standard Chartered was ordered to appear on Aug. 15 to explain the "apparent violations of law" and demonstrate why its licence to operate in New York should not be revoked.
"For almost 10 years, SCB schemed with the government of Iran and hid from regulators roughly 60,000 secret transactions, involving at least $250-billion," the regulator said.
Standard Chartered falsified transaction reports and obstructed oversight "in its evident zeal to make hundreds of millions of dollars at almost any cost."
The transactions mainly involved U.S. dollar transfers for state-owned Iranian banks, including the central bank, that fell under U.S. controls aimed at undermining Tehran's alleged nuclear weapons program.
The activity "left the U.S. financial system vulnerable to terrorists, weapons dealers, drug kingpins and corrupt regimes," the DFS said.
There was also evidence of possible illegal transactions with Libya, Myanmar and Sudan while they were under U.S. sanctions.
The bank, which focuses on Asia, the Middle East and Africa, said it was surprised at the claims as it had informed U.S. agencies in 2010 that it had voluntarily launched an internal compliance review.
It said the review "did not identify a single payment on behalf of any party that was designated at the time by the U.S. government as a terrorist entity or organization".
The bank also said it had stopped all new business with Iranian customers more than five years ago.
"The group takes its responsibilities very seriously, and seeks to comply at all times with the relevant laws and regulations," Ms. Durbin said. "We intend to discuss these matters with the DFS and to contest their position."
The bank could face steep fines if found guilty.
Justin Harper, market strategist for IG Markets in Singapore, said being tagged a "rogue bank" by a U.S. regulator was a severe blow.
"They have got a good reputation in the industry which will be tarnished by these accusations, whether they prove accurate or not," he told AFP.
But Kathy Lien, managing director at the New York-based BK Asset Management, said she doubted the bank would be brought down by the scandal.
"At worst, they will get a slap on the wrist and pay a fine," she said.
In July, a U.S. Senate report accused London-based HSBC of concealing more than $16-billion in sensitive transactions with Iran and Mexican drug lords over 2001-2007.
In June, ING Bank was fined $619-million for its role in processing $1.6-billion through the US financial system for Cuba, Iran, Myanmar, Sudan and Libya.
Last month, Barclays was fined €290-million by British and U.S. regulators after admitting that it attempted to manipulate the Libor and Euribor benchmark interest rates between 2005 and 2009.
The New York regulator said Standard Chartered's illicit Iran business involved thousands of U-turn transactions, in which dollar-denominated payments and transfers are routed into and then out of the United States by non-U.S. entities.
Such deals involving Iranian institutions were strictly limited, and more recently completely banned, under U.S. sanctions against Tehran.
But the regulator, citing internal Standard Chartered documents, said the bank's London office routinely stripped the transactions of any signs that Iranian banks were involved.
"Senior SCB management knowingly embraced the bank's fraudulent U-turn procedures," the department said.
The bank's attitude was captured in a comment from a group executive director, as related to the New York regulator by an officer of Standard Chartered's New York branch.
Using vulgar language, he purportedly asked: "Who are you to tell us, the rest of the world, that we're not going to deal with Iranians?"
In a statement accompanying an interim profit result last week, chief executive Peter Sands lauded the bank's "culture and values".
"We are selective and turn things down that we don't understand, or don't like the look of," he said.