As HSBC is accused of helping companies evade taxes, Channel 4 News looks at five other banking controversies since the financial crash.
Banks were fined in the region of $22bn (£14.5bn) for their part in the Libor fixing scandal.
The London interbank lending rate, Libor, supports trillions of pounds worth of loans. In 2012, British banks were accused of inflating and deflating Libor to encourage a profit from trades.
Barclays chief executive Bob Diamond was forced to resign after his bank was fined £290m for its part in the Libor scandal.
The biggest banking scandal in terms of the number of people affected. Since the 1990s, millions of customers were mis-sold insurance policies to pay off loans or mortgages if they died, became ill or lost their job.
Banks alone are thought to have paid out around £22b in compensation.
As of January 2015, the financial ombudsman dealt with 1.25m complaints – not including complaints made directly to banks and credit card companies.
In 2012, British bank Standard Chartered agreed to pay a $340m fine with the New York state department of financial services (DFS) after being accused of hiding $250bn of transactions with Iran.
The bank was accused of leaving the American financial system susceptible to terrorists and “drug kingpins”.
Two years later, Standard Chartered agreed to pay $300m to DFS after failing to improve its money laundering controls.
Barclays, RBS, HSBC and Lloyds were forced to compensate thousands of small businesses who were mis-sold complex insurance deals.
Rate-swap products were designed to protect firms against rising interest rates. But In 2013, the Financial Standards Authority said that it found 90 per cent of cases it examined did not comply with regulatory requirements.
Barclays set aside £450m for compensation. HSBC, RBS and Lloyds also incurred costs.
In 2014, US and UK regulators imposed a £2.6bn fine on five banks for conspiring to manipulate foreign exchange rates.
Investigators found there was a “free for all culture” rife on the trading floors of RBS, HSBC, Citibank, JP Morgan and UBS.
HSBC was fined £216m, the biggest fine of all British banks.