The woman alleged to be at the heart of one of the world’s biggest cryptocurrency frauds is now on the Federal Bureau of Investigation’s 10 Most Wanted Fugitives list, 

Ruja Ignatova is accused of operating a world-wide pyramid scheme that took in more than $4 billion from 2014 through 2016 through the purported cryptocurrency OneCoin, 

Ms. Ignatova, known among her followers as the Cryptoqueen 

Ms. Ignatova allegedly instructed people from across the world to send money to OneCoin accounts to purchase the cryptocurrency, according to the FBI.

But OneCoin wasn’t actively traded and couldn’t be used to buy anything. 

Federal prosecutors said it was more of a pyramid scheme, with money from new purchasers flowing up to Ms. Ignatova and others who sold the currency in the early days.

OneCoin made so much money that Ms. Ignatova and the other top sellers hardly knew where to put it, according to legal proceedings. 

They stacked it in cash in offices and apartments in Bulgaria, Hong Kong, Dubai and South Korea.

They lent it out and plowed it into stables in Abu Dhabi for thoroughbred racehorses, according to the proceedings.

Ms. Ignatova, a Bulgarian who once worked for McKinsey & Co., was indicted by a federal grand jury in 2017, but remains at large

The FBI is offering a reward of up to $100,000 for information leading to her arrest.