The Vix - everyone's favourite measure of global market volatility - was up 17.3 per cent at 27.42 points in mid-afternoon trading in the US.
The Vix has spiked several times in recent months as turbulence took hold of global markets. In January, it rose as high as 31.36 during intraday trading, while during so-called Black Monday in August it jumped to 40.7.
Its all-time high was in October 2008, when it rose to 79.2.
Global markets have spent the day merrily plummeting, as fears over a potential downturn grew. In the UK, the FTSE 100 closed 2.7 per cent lower at 5,689 points, its lowest since mid-January, while other European markets followed suit, with the German Dax dropping 3.3 per cent and the French Cac falling 3.2 per cent.
In the US, tech stocks dragged the Nasdaq to its lowest in 18 months, with Facebook falling 5.5 per cent and Twitter falling 3.5 per cent.
The S&P 500 was down 2.4 per cent, while the Dow Jones was down 2.4 per cent.
"Investors in the US and Europe are worried by many things, not least the current interest rate outlook in the US," said Chris Beauchamp, senior market analyst at IG.
"Recent surveys of fund managers may indicate rising cash balances, but so far these appear to be remaining on the side lines, pulling the rug from under what remains of this bull market. In a week when economic data is relatively light, it is becoming increasingly apparent investors are struggling to find any positive news on which to create a rally."