By Wallace Witkowski and Anora Mahmudova, MarketWatch

Nasdaq sees worst one-day percentage drop since August 2011

U.S. stocks plunged Friday, closing slightly above session lows, a day after U.K. citizens voted to end the country's membership in the European Union--a historic rejection of Europe's political order.

Investors fear the unprecedented decision could destabilize the region's economy, slowing global growth and threatening financial stability. Wall Street joined a global equity rout that saw even sharper plunges in Europe, move that come after global markets rallied a day earlier on a bet that Britons would vote to remain in the trading bloc.

"The market was pricing in a different outcome yesterday even when the odds were too close to call and within a margin of error. The unexpected outcome is shaking up markets," said Ben Carlson, money manager at Ritholtz Wealth Management.

Read:How bookies blew the Brexit call (http://www.marketwatch.com/story/how-bookies-blew-the-brexit-call-2016-06-24)

On Friday, the main U.S. indexes all closed down more than 3%, wiping out year-to-date gains for both the S&P 500 and the Dow, while adding to the 2016 loss for the Nasdaq.

The S&P 500 dropped 75.91 points, or 3.6% to close at 2,037.41, following an earlier 81-point deficit. Nine of the 10 main sectors closed sharply lower. Financials, materials, and tech stocks led the losses. Utilities closed fractionally higher due to heightened demand for safer, defensive plays.

In a recent note, FactSet said the sectors with revenue most exposed to the U.K. are energy at 6.4%, tech at 4%, and materials at 3.7%.

The Dow plunged 611.21 points, or 3.4%, to close at 17,399.86, all 30 blue-chip stocks finishing lower, led by bank stocks. J.P. Morgan Chase & Co., (JPM) dropped 7% and Goldman Sachs Group Inc. (GS) dove 7.1%. Earlier, the average was down by as many as 655 points.

Meanwhile, the Nasdaq Composite Index plummeted 202.06 points, or 4.1%, to finish at 4,707.98, for its worst one-day percentage drop since August 2011.

The Brexit vote will have wide implications for monetary policy round the globe, according to analysts.

"The vote will definitely make it very difficult for the [Federal Reserve] to raise rates this year, and in fact the [Fed fund] futures are currently giving better chances of a rate cut in the U.S. than a rate increase. Lower for longer is what we continue to expect--the global economy is going to face lower growth prospects and rates are therefore going to be kept lower for longer," said Chris Gaffney, president at EverBank World Markets.

In the middle of the selloff, some veteran strategists were urging calm, and even pointing to buying opportunities (http://www.marketwatch.com/story/why-brexit-crisis-is-a-screaming-buy-for-stock-investors-2016-06-24).

"What is occurring is traders are rushing for the exits and can't get out fast enough," said Robert Pavlik, chief market strategist at Boston Private Wealth, in emailed comments. "As investors we must not panic (I realize the argument comes across as weak especially at this time) but keep in mind that the process for the United Kingdom to exit the European Union will occur over a period of two years and not weeks or months."

See:Here's why Brexit probably isn't a 'Lehman moment' (http://www.marketwatch.com/story/brexit-is-big-but-its-probably-not-a-lehman-moment-2016-06-24)

Fixed income plays have now become wildly expensive while stocks are mor fairly valued, said Mike Baele, senior portfolio manager of the Private client Reserve at U.S. Bank.

"About 60% of the stocks on the S&P 500 now have a better yield than the 10-year Treasury," said Baele. "Any investor with a time horizon can find high quality blue chips with better yields."

On Friday, the Fed said it was prepared to provide dollar liquidity through its existing swap lines with central banks, as necessary, to address pressures in global funding markets, which could have adverse implications for the U.S. economy.

European stock-market indexes were being punished in the aftermath of the vote, with the Stoxx Europe 600 skidding 7% to 321.98.

Read:Will the euro survive Brexit aftermath? (http://www.marketwatch.com/story/how-brexit-triggers-new-worries-about-the-survival-of-the-euro-2016-06-24)

But moves in currencies, in particular, the British pound (http://www.marketwatch.com/story/pound-bounces-sharply-as-brexit-results-come-in-2016-06-23) were the most pronounced. Sterling hit a low of $1.3230, a more than 12% plunge from $1.4871 late Thursday in New York. But it has since recovered somewhat, trading most recently at $1.3627.

Read:Soros looks set to make a killing on Brexit result (http://www.marketwatch.com/story/soros-looks-set-to-make-a-killing-on-brexit-result-2016-06-24)

In the wake of the shocking Brexit vote, U.K. Prime Minister David Cameron said Friday morning he will resign (http://www.marketwatch.com/story/uk-prime-minister-david-cameron-resigns-after-brexit-vote-2016-06-24). Cameron has been campaigning for the "remain" camp.

In other assets:Gold (http://www.marketwatch.com/story/brexit-result-sends-gold-futures-surging-to-2-year-high-2016-06-24), which had surged more than $70, settled up $59.30, or 4.7%, to $1,322.40, and yields on the benchmark 10-year U.S. Treasury fell to 1.57% as investors flocked to safety.

Oil prices (http://www.marketwatch.com/story/crude-oil-prices-walloped-as-uk-votes-in-favor-of-brexit-2016-06-24) dropped $2.47, or 4.9%, to settle at $47.64 a barrel as the U.S. Dollar Index jumped 2.2%.

On the data front: Economic data was overshadowed by the Brexit vote. Market reaction to durable-goods orders was muted. Consumer sentiment sank to 93.5 in June, according to the University of Michigan.

Corporates:Newmont Mining Corp.(NEM) closed up 5.1%, following a historic jump in gold prices to the highest level in two years, and despite the fact that it has the highest percentage revenue exposure to the U.K (http://www.marketwatch.com/story/brexit-fallout-may-be-more-about-fear-than-fundamentals-1-stocks-move-suggests-2016-06-24). than any other company on the S&P 500.

More than nine-tenths of the S&P 500's stocks closed lower, however. Banking stocks were hit the hardest. Citigroup Inc. (C) closed down 9.3%, Morgan Stanley(MS) dropped 10%, and Bank of America Corp. (BAC) tumbled 7.4%.

Oil companies were among the biggest losers. Chesapeake Energy Corp.(CHK) was down 5.8%, Transocean Ltd.(RIG) fell 6.3%.

The worst performers on the S&P 500 were Delphi Automotive PLC(DLPH), Invesco Ltd., Charles Schwab Corp.(SCHW), Lincoln National Corp.(LNC), and Priceline Group Inc.(PCLN), all closing down 12% or more.

--Mark DeCambre in New York contributed to this article.

(END) Dow Jones Newswires

June 24, 2016 16:30 ET (20:30 GMT)