(For a live blog on the U.S. stock market, click or type LIVE/ in an Eikon news window)
* Markets turn sharply lower in mid-afternoon trading
* Apple hits record high as new iPhone launch date announced
* Canada-U.S. trade talks near Friday deadline
* Dollar General, Dollar Tree hit by margin worries
* Indexes down: Dow 0.44 pct, S&P 0.33 pct; Nasdaq 0.06 pct (Updates to late afternoon, changes dateline to NEW YORK, changes byline)
By Stephen Culp
NEW YORK, Aug 30 (Reuters) - U.S. stocks ended their four-day winning streak on Thursday as investors sold risk ahead of the long holiday weekend.
The broad-based sell-off steepened mid-afternoon in the midst of ongoing trade talks.
The CBOE Volatility index, a gauge of investor anxiety, rose to its highest level in over a week.
"It makes sense, especially given the run we've had, that some investors and traders just don't want to hold risk going into the long weekend," said Shawn Cruz, manager of trader strategy at TD Ameritrade in Jersey City, NJ.
"It will be interesting to see what shakes out in the markets when everyone comes back from vacation next week," Cruz added.
China kept its tariff dispute with the United States in focus as its commerce ministry insisted negotiations must be based on "equality," with Washington's proposed tariffs on an additional $200 billion of Chinese goods going into effect next month.
China's statement coincided with continuing efforts by Canada and the United States to revamp the North American Free Trade Agreement (NAFTA) ahead of a Friday deadline.
Apple Inc shares hit a record high, and were up 1.5 percent following news that it would unveil its latest iPhones on September 12.
The Dow Jones Industrial Average fell 115.48 points, or 0.44 percent, to 26,009.09, the S&P 500 lost 9.58 points, or 0.33 percent, to 2,904.46 and the Nasdaq Composite dropped 5.25 points, or 0.06 percent, to 8,104.44.
All of the 11 major sectors of the S&P 500 were trading lower.
Tesla looked set to close below $300 for the first time since the end of July as the electric car maker extended its decline in the wake of Chief Elon Musk's decision to scrap his take-private plans.
Campbell Soup Co shares dipped 2.2 percent after it announced plans to sell its international and fresh refrigerated-foods units and left open the possibility of putting the whole company up for sale.
Shares of Abercrombie & Fitch Co plunged 18.0 percent after the apparel retailer missed quarterly same-store sales estimates.
Discount retailers Dollar Tree Inc and Dollar General Corp were down 14.9 percent and 1.7 percent, respectively, after both gave disappointing profit outlooks on margin worries.
Amazon.com stock rose 0.5 percent, edging the company closer to becoming the second U.S. company after Apple Inc to reach $1 trillion in market value.
In economic news, the Federal Reserve's preferred inflation gauge, the core PCE price index, posted a 2 percent year-on-year increase, hitting the central bank's target and boosting the likelihood of additional rate hikes this year.
Declining issues outnumbered advancing ones on the NYSE by a 1.76-to-1 ratio; on Nasdaq, a 1.18-to-1 ratio favored decliners.
The S&P 500 posted 30 new 52-week highs and 1 new lows; the Nasdaq Composite recorded 96 new highs and 31 new lows. (Reporting by Stephen Culp Editing by Chizu Nomiyama)