Moritz Erhardt, a 21-year-old intern on a summer placement, was found dead in the shower at his temporary accommodation in east London last August.
It was reported that Erhardt died after he suffered an epileptic fit following three consecutive all-nighters as part of his internship. His death sparked a debate about long working hours for banking interns and junior staff.
The German student was a week from completing a placement at Bank of America Merrill Lynch's London offices, and was due to be offered a job at the bank.
An inquest at Poplar Coroner's Court in east London heard that Erhardt was taking medication for epilepsy, but had not told anyone at the bank about his condition.
Coroner Mary Hassell said: "One of the triggers for epilepsy is exhaustion and it may be that because Moritz had been working so hard, his fatigue was a trigger for the seizure that killed him."
She said it was "only a possibility" and she did not want his family to "go away with the thought that it was something that Moritz did" that caused his death.
"He was a young man living life to the full and he was clearly enjoying his time in London and, while it's possible that fatigue brought about the fatal seizure, it is also possible that it just happened. And it is something that does just happen."
Erhardt's death raised concerns about the long-hours culture at top City banks. Merrill Lynch has confirmed is reviewing its working practices and culture.
Hans-Georg Dieterle, Erhardt's 51-year-old father, last month called for the UK Government to revise working hours and employment laws.
He said he would like to see the Government introduce legislation to protect workers from excessive hours.
