Four giants of global banking agreed Wednesday to pay more than $5 billion in fines to regulators and plead guilty to manipulating the global currency market.

___

WHICH BANKS ARE INVOLVED?

Traders at four banks — JPMorgan Chase, Citigroup, Barclays and the Royal Bank of Scotland — conspired to fix rates on U.S. dollars and euros at the expense of clients from 2007 to 2013. Another bank, Switzerland's UBS, agreed to plead guilty to manipulating key interest rates and will pay a separate criminal penalty.

___

WHAT DID THE TRADERS DO?

The traders used chat rooms to coordinate currency trades to their advantage. They also shared confidential orders to position themselves to profit from those orders. In a hypothetical example, Company A could have told a bank to buy $1 billion in euros. A trader at that bank could have told traders at rival banks to bid up the euro in order to take advantage of Company A's buying.

___

WHAT'S THE CRIME?

JPMorgan, Citi, Barclays and RBS will plead guilty to conspiring to fix rates and manipulate the market.

UBS also participated in this scheme, but was not charged for the crime because it helped prosecutors with the investigation. The bank is pleading guilty to an earlier act of manipulating key interest rates. UBS had settled that charge with regulators in 2012 in what's known as a "non-prosecution" agreement. But UBS violated that agreement, prosecutors say, by participating in the currency market manipulation.

___

WHAT IS NOTABLE ABOUT THE GUILTY PLEAS?

It's rare that a major U.S. financial institution is found guilty of criminal behavior, despite years of financial scandals and billions spent to settle issues tied to the financial crisis.

The last U.S. bank to be convicted of a comparable felony was junk bond bank Drexel Burnham Lambert in the late 1980s. Two Swiss banks — Credit Suisse and UBS — were found guilty last year of helping Americans commit tax evasion. Both got wavers to continue doing business in the country.

___

HOW BIG IS THE CURRENCY MARKET?

Each day, $3.4 trillion worth of euros, yen, U.S. dollars and Swiss francs are traded between major banks on behalf of companies doing business internationally. The size of the stock market pales in the comparison. With globalization, the foreign exchange market has become larger and even more important.

___

WHY IS IT IMPORTANT?

Unlike stock and bond markets, the world's foreign exchange market trades nearly 24 hours a day, seven days a week, all year. However, trading pauses at two key moments each day. These moments, known as "the fix," are important for every company and every investor. The fix allows companies to calculate the value of their foreign holdings every day. It also allows people who own stocks, bonds and other investments that are priced in foreign currencies to figure out their value in local currency. In the case announced on Wednesday, traders at the banks coordinated their currency trades ahead of "the fix."