By Saqib Iqbal Ahmed NEW YORK (Reuters) - Wall Street's top 'fear gauge' jumped to a fresh eight-month high on Friday as U.S. stocks opened sharply lower after China imposed fresh tariffs on all U.S. goods in response to the Trump administration's sweeping levies. The Cboe Volatility Index - an options-based gauge of stock investors' anxiety about the market's near-term outlook - rose as much as 15.54 points to a 45.56, its highest since August. The index was last up 8.25 points to 38.27. "A VIX at 40 is a sign of fear for sure," said Joe Tigay, portfolio manager for Rational Equity Armor Fund. "Usually you see a 40 when there's something more than the usual sell-off ... some sort of credit risk, margin risk, something that could cause a contagion that could spill over and across to other asset classes," Tigay said. Investors, who have been battered by a sharp selloff this year - the S&P 500 is down about 11% for the year - have been keeping an eye on the volatility gauge as an indicator of market stress. In the last 10 instances when the S&P 500 experienced a correction - a fall of 10% or more from a recent high - the VIX on average touched a peak level of 37 before the selling was done. (Reporting by Saqib Iqbal Ahmed; Editing by Chizu Nomiyama)