An employee at the Australian Securities Exchange head office in Sydney has tested positive to the coronavirus and about 20 others who work there are in isolation.
The employee, who is based at the company's Bridge Street head office, returned a positive COVID-19 test on Saturday.
"The employee has mild symptoms, is in good spirits and is not required to be hospitalised," the company said in a statement on Sunday.
About 20 other ASX employees that had close contact with the infected person are also self-isolating and the office has been thoroughly cleaned.
As a further precautionary measure, the company has asked employees across various sites - including Bridge Street, the Australian Liquidity Centre, secondary data centre and interstate and overseas offices - to work from home until further notice
The only exception are a "core group of employees" who will remain on ASX sites to manage ongoing market functions, mainly in operations, surveillance and technology, it said.
"We will continue to be informed by the advice of health authorities and the government, and take a cautious approach to ensure the wellbeing of our people and ongoing confidence of our stakeholders," the company said.
The ASX operates Australia's largest share market.