The investigation into Libor rigging, a benchmark interest rate tracking cash borrowing costs, ended unexpectedly.
This decision comes despite evidence suggesting the Bank of England.
This means no banks will be charged in the UK for so-called "low-balling" charges.
The Serious Fraud Office (SFO) said a detailed review of the decision came out.
Regarding Libor rigging, the SFO has prosecuted 13 traders and money brokers for four years.
The US Justice Department (DoJ) has prosecuted six people.
Eleven additional traders were prosecuted for the manipulation of Euribor, the Eurozone libor. The SFO said the side of the Euribor investigation is still open.
The SFO said in a statement: "After a thorough investigation and detailed review of the available evidence, we will no longer be prosecuted in this case. This decision was made in accordance with the Crown Prosecutor's Test."
The Code states that the evidence must support realistic convictions and be in the public interest.
What is Libor?
What the FTSE 100 Index shares price, Libor is an index that tracks interest rates, or cash borrowing costs. Millions of mortgages and commercial loans around the world have interest rates associated with Libor.
Every day, banks estimate the interest rate they need to pay to borrow money, and the average is announced as the Interbank Bank Interest Rate.
SFO and DoJ indicted the trader by requesting a Libor estimate to request to cut or lower by one hundredth or one hundredth point or one hundredth of a percentage to match the bank's trading position associated with Libor average. .
However, more traders were acquired than convicted.
In the United States, two-month traders Matt Connolly and Gavin Black are waiting for a sentence later this month.
Connolly went public to protest his beliefs. His lawyers told the court that it was accepted as a commercial practice for merchants to request a high or low Libor estimate for the bank's commercial interests within the exact estimate of cash loan costs.
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Requests for even greater fluctuations in Ribo estimates-up to 50 times the fluctuations pursued by traders-were fined by senior managers of the bank during the credit crunch of 2007-2009.
Senior executives feared that acknowledging the high interest rates that banks are paying to get scarce funds could lead to bad publicity and drop bank shares.
During the 2007-2009 financial crisis, the Bank of England intervened in the process of establishing Libor, which is concerned with financial stability.
The low-altitude evidence acquired by the BBC has pledged secret audio recordings implying the Bank of England from 2008 and the testimony that the United States Department of Justice announced that Barclays would lower Libor estimates by the Bank of England from September 1. 2007.
But Barclays senior banker and Bank of England executives told Congress in 2012 that they did not know about low bowling until 2012.
When the secret audio aired in April 2017, the MP called for an immediate inquiry. The Bank of England said that Libor was not regulated at the time.
At the Libor trial, the lawyer questioned why the SFO prosecuted or prosecuted anyone regarding low bowling.
The SFO told the court that an investigation into savings is underway. Recently, the SFO repeated this stance in May 2019, telling journalists that it is still investigating its practices.
The SFO said that Sara Lawson QC's legal adviser decided to close the Libor investigation because director Lisa Osovsky was withdrawn from the Libor case.
Mr. Osovsky has background knowledge of the role of the executive, including the deputy director of the FBI who investigated Libor rigging.