"I know that you are ALL working very hard and are stretched thin across multiple projects," the email stated.
"Given that new staffings continue to flow in and you are all very near capacity, the only way I can think of to differentiate among you is to see who is in the office in the wee hours of the morning.
"I know that everyone works differently and you all likely have a docking station set up at home, but I have found that when you are truly jammed with no end in sight, you should stay in the office because the connection is faster, your associates (and potentially VPs) are in close proximity, and you have access to firm resources.
"That said, this method isn't perfect and if you have any suggestions on how I can do this more accurately, I'm all ears."
The brutal email is all the more shocking given that, in 2015, Moelis & Co junior banker Thomas Hughes, 29, took his own life.
According to family members, Hughes had returned from a business trip and then immediately went to the office and worked from 6pm to 1am on the day of his death.
He then worked from home until 9.45am, before passing away at 10am.
Hughes had drugs in his system at the time of his death, and his relatives claimed his drug use and suicide was at least partially the result of work stress.
There have also been a number of high-profile deaths of young bankers at other US banks.
In April 2015, Goldman Sachs analyst Sarvshreshth Gupta, 22, committed suicide after allegedly telling his father he hadn't slept for two days due to his excessive workload.
And in 2013, 21-year-old Bank of America intern Moritz Erhardt died after allegedly working for 72 hours straight.
The epidemic has prompted the industry to improve the work/life balance of staff by limiting weekend work and encouraging employees to leave the office.
According to the Financial Times, a company spokeswoman said: "We put a lot of trust in our people, including our junior staff, knowing they can complete their work effectively whether or not they are directly supervised or physically sitting at their desks."
Comments under the original Wall Street Oasis post were mixed, with one reader writing: "This is how all top investment banks work ... better get used to it or choose a different industry buddy," while another wrote, "The staffer basically accuses people of being lazy ... This is why people aren't going into banking."