Global stock markets are on course for their worst week since the 2008 financial crisis amid fears over the coronavirus outbreak.
New York's Dow Jones recorded its biggest one day points fall in history. The Wall Street index fell by 1,191 points or 4.4 per cent.
Earlier on Thursday the FTSE-100 suffered its biggest one day fall in percentage terms since August 2015.
Bond prices soared again, sending the yield on the 10-year Treasury to another record low.
When yields fall it's a sign that investors are feeling less confident about the strength of the economy going forward.
The latest losses extended a slide in stocks that has wiped out the solid gains the major indexes had posted early this year.
The S&P 500 is now 12 per cent below the all-time high it set just a week ago. This is now the stock market's worst week since October 2008, when Wall Street was mired in the financial crisis.
It comes as the UK recorded its 16th case of coronavirus after Northern Ireland's Chief Medical Officer confirmed the province's first victim.
The first positive test for coronavirus in Northern Ireland was confirmed at a briefing in Belfast on Thursday evening.
Northern Ireland’s Public Health Agency said it was “working rapidly” to identify anyone the patient came into contact with to prevent a further spread.
The patient had recently returned from northern Italy and had previously been in Dublin.
Another of the UK's new cases, a parent at a Buxton primary school in Derbyshire, contracted the virus in Tenerife, where Britons are being kept in a quarantined hotel on the south west of the island.
The third patient also contracted the virus in Italy, which has become the worst affected country in Europe with more than 400 cases and 14 deaths.
Italy has become the centre of the outbreak in Europe, with the spread threatening the financial and industrial centres of that nation.
The virus has now infected more than 82,000 people globally and is worrying governments with its rapid spread beyond the epicentre of China.
Japan will close schools nationwide to help control the spread of the new virus.
Saudi Arabia banned foreign pilgrims from entering the kingdom to visit Islam’s holiest sites.
At their heart, stock prices rise and fall with the profits that companies make and Wall Street’s expectations for profit growth are sliding away.
Apple and Microsoft, two of the world’s biggest companies, have already said their sales this quarter will feel the economic effects of the virus.