HSBC has already been fined £1.2bn for breaching money-laundering rules and Royal Bank of Scotland and Barclays hit with major penalties for rigging Libor, but over the past two weeks Britain's major banks have warned shareholders of the wide range of investigations they still face that could lead to even more fines.

Some of the information in more than 30 pages of legal disclosures released during the banks' recent results dates back more than 10 years – such as HSBC's admission about a long-running complaint relating to its takeover of Household International in the US in 2002. Other details reveal a common theme, such as ongoing investigations into Libor rigging that saw Barclays and RBS pay £290m and £390m respectively.

A number of the banks cite the implications of a competition investigation into interchange fees in the MasterCard network as well as European investigation into credit default swaps, the derivatives that were thrown into focus during the eurozone crisis when they provided a gauge to market fears of a country defaulting on its debt.

In many instances the banks are unable to quantify, as yet, the impact of ongoing cases – although RBS provided the most detailed warning of potential future fines by setting aside £385m to cover legal costs associated with unspecified regulatory actions.

HSBC

■ The bank faces litigation dating back to 2002 over its acquisition of Household International and alleged misleading statements about its consumer lending division. The case should be completed next month, but HSBC says it will have grounds for appeal. The bank has set aside $3.5bn.

■ The jailing of Bernie Madoff for 150 years left HSBC facing various claims, as it acted as a custodian and administrator to a number of Madoff funds. It is not able to quantify the size of any losses.

■ The US Federal Housing Finance Agency, which oversees mortgage companies Fannie Mae and Freddie Mac, is suing over the selling of mortgage-backed securities and could land HSBC with a $1.6bn bill. The bank warned there may be "additional claims litigation and governmental and regulatory scrutiny".

■ Already fined $1.9bn for breaking anti-money-laundering rules, the bank is subject to a deferred prosecution agreement with the US department of justice. Private litigation is not ruled out.

■ An ongoing investigation in the US into whether some customers should have reported US tax could leave the bank with "significant" penalties.

■ Investigation into Libor rigging could leave HSBC facing "fines and penalties" which "could be significant". It is also named in private lawsuits.

■ The European commission investigation into credit default swaps is looking at anti-competitive behaviour between 2006 and 2009. HSBC warns that it cannot assess the impact of this investigation, and class actions have been filed in federal courts in Chicago and New York.

BARCLAYS

■ After it acquired the Wall Street operations of the collapsed Lehman Brothers in 2008, the trustee of the estate complained about the terms of the deal. Barclays admitted it could lose out if it receives no money from the liquidators of Lehman but warned there was a "significant degree of uncertainty".

■ Five class-action suits on behalf of US shareholders argue that Barclays gave misleading statements about the value of its mortgage-related assets between 2006 and 2008. Barclays is defending the cases and warns it cannot estimate potential losses.

■ The Federal Housing Finance Agency is also investigating Barclays over mis-selling of mortgage-backed securities.

■ The Office of Fair Trading (OFT) and other competition authorities are investigating Visa and MasterCard interchange fees – Barclays warns it is not possible to predict the outcome.

■ Having fined Barclays £290m for rigging Libor, the New York attorney general subpoenaed the bank and others for information. Barclays is not able to estimate the financial impact.

■ It is fighting a $470m penalty by the US federal energy regulatory commission over power trading in California.

■ The European commission is looking at accusations of anti-competitive behaviour in the credit default swap market – Barclays is not able to assess the impact or timing.

■ The bank has received preliminary findings of the investigation by the UK's Financial Conduct Authority (FCA) into the disclosure of fees at the time of its 2008 fundraisings. It is contesting the findings. The Serious Fraud Office and the US authorities are also investigating.

LLOYDS BANKING GROUP

■ The bank is facing claims in the German courts over policies issued by its insurance arm Clerical Medical, for which a £400m provision has been made. It warned the final tally "could be significantly different".

■ In talks with the Prudential Regulation Authority, the FCA and others over undisclosed matters, a £100m provision was taken in 2012.

■ The competition investigation into interchange fees paid through MasterCard is ongoing and the impact will only be known once completed.

■ Some parts of the group have received requests for information in the Libor-rigging investigation but Lloyds is not able to predict the outcome and scope of the analysis.

■ A complaint from shareholders in the US about "material omissions" in statements issued during the rescue takeover of HBOS has been rejected in a US court but is now the subject of an appeal. Lloyds says it is without merit.

■ It is awaiting the outcome of a report by the Financial Services Authority (FSA) into what went wrong at HBOS.

ROYAL BANK OF SCOTLAND

■ RBS faces class actions in the US and in the high court from shareholders complaining about the accuracy of financial information published by the bank in public documents.

■ It is also being investigated alongside HSBC and Barclays by the Federal Housing Finance Agency over the selling of mortgage bonds.

■ On top of a £390m fine for rigging Libor, complaints have been filed in the US alleging that the bank broke federal laws. RBS is contesting them and continues to co-operate with ongoing investigations.

■ The European commission is investigating anti-competitive behaviour in the credit default swaps market, which RBS is defending.

■ Trustees for the bankrupt Madoff estate are seeking more than $200m from RBS, which the bank is defending.

■ It faces enforcement action from the FCA over its IT failure in 2012 and has warned of litigation from customers.

■ The impact of the competition investigation into interchange fees paid through MasterCard, it said, would only be known once completed.

■ A mystery shopping exercise by the FSA into how RBS provided investment advice to customers required the bank to review its training procedures. RBS has warned it could be forced to appoint an independent third party to oversee the work.■ The OFT investigation into competition in small business banking launched in June could have a "material impact" on the bank.

■ A cease and desist order issued in July 2011 over risk management and compliance systems in its US operation RBS Citizens is still in place after it was accused of "deceptive marketing". Citizens neither admitted nor denied the allegations.

■ An investigation over its compliance with US economic sanctions could have a "material adverse" effect on its results.

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