U.S. stock-index benchmarks slumped to start Friday trade, tracking a global equity retreat fueled by a mounting currency crisis in Turkey, which raised the alarm for possible contagion into other markets. The Dow Jones Industrial Average DJIA, -0.32% fell by 210 points, or 0.8%, at 25,29, the S&P 500 index SPX, -0.22% fell 0.6% at 2,833, while the Nasdaq Composite Index COMP, +0.03% dropped 0.6% at 7,847. The drop for stocks to close out the week comes amid a steep decline in the Turkish lira TURUSD after the European Central Bank expressed concern about the country, where President Recep Tayyip Erdogan was re-elected in a snap vote in June and whose growing power has raised questions about the independence of the country's central bank. Meanwhile, newly announced U.S. sanctions against Russia added to the turmoil. The the ruble USDRUB, +1.74% shed as much as 5% against the dollar on Thursday and stock averages there plunged. In corporate news, shares of Dropbox Inc. DBX, +2.07% were lower after a second-quarter earnings report, which also included news that Chief Operating Officer Dennis Woodside was stepping down and a post-IPO lockup on shares would expire earlier than previously planned.