Legal tussles seem never ending for big banks. Recently, seven major banks settled a private U.S. lawsuit in Manhattan federal court for a penalty amount of around $324 million, according to Reuters. The banks in question were accused for manipulation of ISDAfix rates, a benchmark used to appraise interest rate derivatives, commercial real estate mortgages and structured debt securities.The banks – Bank of America Corp. BAC, Barclays PLC BCS, Citigroup Inc. C, Credit Suisse Group AG CS, Deutsche Bank AG DB, JPMorgan Chase & Co. JPM and The Royal Bank of Scotland Group plc RBS – are currently awaiting an approval from the court which will also settle the antitrust charges against the banks.Notably, 14 banks were sued by numerous pension funds and municipalities for manipulating the ISDAfix benchmark for personal gains in the 2009–2012 period.Meanwhile, under the latest settlement, JPMorgan will pay $52 million, Bank of America, Credit Suisse, RBS and Deutsche Bank will cough up $50 million each, while Citigroup will expend $42 million and Barclays will shell out $30 million.The remaining banks under purview of investigation are BNP Paribas SA, The Goldman Sachs Group Inc. GS, HSBC Holdings Plc HSBC, Morgan Stanley MS, Nomura Holdings Inc. NMR, UBS Group AG UBS, Wells Fargo & Company WFC and U.K.-based ICAP Inc. – the former administrator for ISDAfix rates.Per the allegations, the banks colluded to rig ISDAfix rates by rapidly executing trades just before the rate was supposed to be determined and delaying the processing of trades until it was fixed. This allowed the banks to manipulate the payments made to investors on derivative trades. Such action adversely impacted trillions of dollars of financial instruments tied to ISDAfix rates.Previously, in Mar 2016, the attempts of the banks to steer clear of investors suffered a major setback after a federal judge in Manhattan rejected their bid to discard the abovementioned private lawsuit.U.S. District Judge Jesse Furman permitted investors led by several pension funds and municipalities to pursue antitrust and breach-of-contract claims over ISDAfix rigging against most defendants. The Alaska Electrical Pension Fund and other investors raised “plausible allegations that a conspiracy among the defendants existed,” Furman stated.Last year, Barclays agreed to pay a penalty of £74.2 million ($115 million) to the U.S. Commodity Futures Trading Commission to settle ISDAfix manipulation charges.Notably, several major banks have been charged for manipulating the London Interbank Offered Rate (LIBOR). Notably, LIBOR is an important benchmark that financial institutions use to set interest rates in trillions of dollars worth of loans and investments.Manipulation of benchmark interest rates by major financial institutions have triggered thorough investigations by regulatory bodies across Europe, Asia and America and claimed billions of dollars as settlements and fines. We look forward to the gradual resolution of such matters which will put long-drawn investigations to rest and bring reprieve to the banks. However, it is likely to deal a huge blow to their financials.Meanwhile, regulatory authorities are thoroughly investigating issues related to the increasing occurrence of foreign exchange rate fixing and are determined to propose a landmark judgment to terminate such practices and bring justice to the wronged. Want the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report >>Want the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report JPMORGAN CHASE (JPM): Free Stock Analysis Report WELLS FARGO-NEW (WFC): Free Stock Analysis Report CITIGROUP INC (C): Free Stock Analysis Report BANK OF AMER CP (BAC): Free Stock Analysis Report CREDIT SUISSE (CS): Free Stock Analysis Report UBS GROUP AG (UBS): Free Stock Analysis Report BARCLAY PLC-ADR (BCS): Free Stock Analysis Report DEUTSCHE BK AG (DB): Free Stock Analysis Report ROYAL BK SC-ADR (RBS): Free Stock Analysis Report NOMURA HLDG-ADR (NMR): Free Stock Analysis Report MORGAN STANLEY (MS): Free Stock Analysis Report GOLDMAN SACHS (GS): Free Stock Analysis Report HSBC HOLDINGS (HSBC): Free Stock Analysis Report To read this article on Zacks.com click here. Zacks Investment Research