Thirty-four year old Jerome Drean took eight separate final exams for 22-year-old economics undergraduate Elnar Askerov over a year-and-a-half.
Credit Suisse's former head of European equity derivatives trading bore no resemblance to the Azerbaijani economics student, but fooled the University of York with a fake ID card.
After both pleading guilty at Britain's York Crown Court to conspiring to defraud the university between January 2006 and May 2007, the pair were told they could face jail for their crimes.
Judge Stephen Ashurst said: "The fact you have admitted the offence goes in your favour, but this is an unusual and serious case of dishonesty. I want you to both understand, and you are clearly intelligent men, that all sentencing options including custody will be considered."
However, the two pleaded not guilty to eight charges of using the false ID with intent, as the men's defence QC claimed they had not realised their actions constituted a criminal offence.
Accordingly, Mr Drean denied one charge of acquiring criminal property and one charge of possessing criminal property.
The two men will be sentenced next month.