UPDATE: The street has now reopened following the glass's removal.
A street in Sydney's CBD has been closed to cars and pedestrians due to fears a loose pane of class could fall.
The bulging pane is on the 18th floor of the Allianz Centre building on Market Street; there's concerns the pane of glass could be caught by the wind and land on passing cars or pedestrians.
"It could have been disastrous," one Allianz Centre worker told AAP.
"Emergency services have done very well with their due diligence by identifying it and acting so quickly."
A glazier at the scene said the pane likely weighed between 70 and 80 kilograms.