Morgan Stanley said that an employee at its suburban New York office has tested positive for the coronavirus disease.

The bank conducted a "deep cleaning" of the Purchase office after making the discovery, the New York-based firm told employees Tuesday in an email. The building houses much of the firm's wealth management operations and more recently was made a backup site for the bank's traders amid contingency planning for the spread of coronavirus.

"We wanted to make you aware than an employee based in Purchase has tested positive for the coronavirus disease," the bank said in the email obtained by CNBC. "Fortunately, the employee was already self-quarantined for some time and is doing well and recovering at home."

Morgan Stanley is the latest Wall Street firm to report an employee was found with coronavirus, just as banks enacted contingency plans including splitting up trading desks by sending workers to backup offices. Yesterday, Wells Fargo told Bloomberg News that a worker in San Francisco had the disease. Then, earlier Tuesday, Barclays and BlackRock each confirmed that an employee in the firms' respective New York offices tested positive.

"We are working closely with the Centers for Disease Control and Prevention (CDC) and other local authorities, and are following their advice," a Barclays spokeswoman told CNBC. "We have also identified colleagues and clients who had had close contact with our affected colleague, and have advised those colleagues to self-quarantine in line with CDC guidance."

BlackRock said the midtown Manhattan office with the impacted employee remains open and that the firm "has been taking all precautions and preventive measures to maintain a clean and healthy environment for our employees and our clients."