Video-conferencing software firm Zoom shares sunk in Wall Street pre-trading after positive signs of a Covid-19 vaccine breakthough.
Zoom shares collapsed 17 per cent as Wall Street opened trading this afternoon to trade at $415.
Shares in the lockdown mainstay pared losses somewhat, but are currently still down 13.2 per cent from Friday, at $433 per share.
Pfizer said this morning its experimental vaccine was more than 90% effective in preventing Covid-19 based on initial self-reported data from a large study, a major victory in the fight against a pandemic.
Pfizer and German partner BioNTech are the first pharmaceutical firms to show successful data from a large-scale clinical trial of a coronavirus vaccine.
The companies said they have so far found no serious safety concerns.
Pfizer expects to seek US emergency use authorization later this month.
Zoom has been one of the few companies to see its value rocket during the pandemic.
The video conferencing app became a mainstay of work-from-home settings during the pandemic.
Shares in the company rose from $70 in February to more than $560 over the last nine months.
The falls for Zoom and lockdown stars Netflix, Peloton and Amazon were rare as the S&P 500 and Dow hit record highs moments after the open.