US STOCKS-Wall St plunges on fears of coronavirus pandemic

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* Indexes drop: Dow 3.56%, S&P 3.35%, Nasdaq 3.71%

* Energy, technology stocks lead the slide

* Wall Street's fear gauge surges to over 1-yr high

* Health insurers fall after Sanders' Nevada victory (Updates to close, adds commentary)

By Sinéad Carew

New York, Feb 24 (Reuters) - Wall Street's three major averages plunged on Monday as investors ran for safety after a surge in coronavirus cases outside China fanned worries about the global economic impact of a potential pandemic.

Investors sold riskier assets and rushed to traditionally safer bets such as gold and U.S. Treasuries after countries including Iran, Italy and South Korea reported a rise in virus cases over the weekend even as China eased curbs with no new cases reported in Beijing and other cities.

The benchmark S&P 500 index and the blue-chip Dow turned negative for the year to date and the Dow dropped more than 1,000 points, only the third time in its history for such a large decline in one day. Both the Dow and the S&P clocked their biggest one-day percentage declines since February 2018.

The technology heavy Nasdaq had the biggest percentage drop, down 3.71%.

"We're not likely to make any progress higher until we have evidence the spread of the coronavirus is decelerating," said Mark Luschini, chief investment strategist at Janney Montgomery Scott in Philadelphia.

The Dow Jones Industrial Average fell 1,031.61 points, or 3.56%, to 27,960.8, the S&P 500 lost 111.86 points, or 3.35%, to 3,225.89 and the Nasdaq Composite dropped 355.31 points, or 3.71%, to 9,221.28.

All of the 11 major S&P sectors closed in the red, led by the energy sector's 4.7% decline and followed by a 4.2% drop in technology stocks.

Apple Inc slid 4.8% as data showed sales of smartphones in China tumbled by more than a third in January.

China-exposed chipmakers fell, with the Philadelphia SE Semiconductor index dropping 4.8%, while concerns about growing travel curbs dragged the NYSE Arca Airline Index down 6%.

Of the S&P's sectors, the defensive utilities, real estate and consumer staples indexes fell the least on the day.

Treasury yields fell to their lowest levels since 2016 as investors sought safety in government bonds, while the yield curve inversion between the 3-month and 10-year U.S. Treasuries deepened in what is often viewed as a recession predictor.

Adding to worries, Goldman Sachs slashed its U.S. growth forecast on Sunday and predicted a more severe impact from the epidemic.

The CBOE Volatility Index, a gauge of investor anxiety, registered its biggest one-day jump since February 2018 and ended the day at 25.03, its highest closing level since January 2019.

"There was this underlying concern that was out there, and obviously over the weekend, it just escalated," said Stacey Gilbert, portfolio manager for derivatives at Glenmede Investment Management in Philadelphia.

Wall Street's three main indexes had notched record highs last week, partly on optimism that the global economy, supported by central banks, would be able to snap back after short-term weakness related to the virus.

The S&P 500 fell below its 50-day moving average and the Dow slipped below its 100-day moving average, all closely watched technical indicators.

Health insurers such as UnitedHealth Group Inc and Cigna Corp dropped almost 8% after Senator Bernie Sanders, who backs the elimination of private health insurance, strengthened his position for the Democratic presidential nomination with a victory in the Nevada caucuses.

Janney Montgomery Scott's Luschini said that while the coronavirus was "by far and away the primary influence" for the market's decline on Monday, investors, he said, were "also beginning to handicap the odds of Sanders being the Democratic nominee."

In a rare bright spot, Gilead Sciences Inc, whose antiviral remdesivir has shown promise in monkeys infected by a related coronavirus, rose 4.6%.

Declining issues outnumbered advancing ones on the NYSE by a 6.74-to-1 ratio; on Nasdaq, a 6.02-to-1 ratio favored decliners.

The S&P 500 posted seven new 52-week highs and 23 new lows; the Nasdaq Composite recorded 21 new highs and 154 new lows.

On U.S. exchanges, 10.51 billion shares changed hands, compared with the 7.79 billion average for the last 20 sessions.

(Additional reporting by Lewis Krauskopf, April Joyner, and Stephen Culp in New York and Medha Singh in Bengaluru; Editing by Arun Koyyur, Chizu Nomiyama and Dan Grebler)