The Dow Industrials Plunge: DealBook Briefing FEB. 5, 2018 Stocks plunge. An afternoon sell-off in United States stocks quickly gain momentum.The Dow Jones industrial average plunged more than 1,500 points, or 6 percent. The blue-chip index was down more than 950 points in recent trading. At the day’s lows, the S.&P. 500 and the Nasdaq Composite Index were down 4.3 percent and 3.6 percent. The two indexes were recently off 2.9 percent and 2.4 percent, respectively. Numbers • The C.B.O.E. Volatility Index surged more than 100 percent to 35.73. • All 11 S&P 500 sectors are down. • The Dow was down 5 percent from its record highs. That’s the first time the index has endured a pullback of that magnitude since the June 2016. • The S.&P. 500 Energy sector was down 3.5 percent • The KBW Nasdaq Bank Index was off 3.5 percent. Wells Fargo declined 8.8 percent. Kenneth C. Griffin sees warning signs for stocks. As the U.S. stock markets look wobbly for the first time in nearly two years, at least one major investor is sounding a bearish tone. In a Jan. 31 letter to investors, Kenneth C. Griffin, founder of the Chicago hedge-fund firm Citadel, wrote that even though the broader economic backdrop continues to be positive, he sees several warning signs that could turn stock prices downward. The end of the Federal Reserve’s efforts to stimulate the U.S. economy is one factor, Mr. Griffin wrote, that could pressure stocks. But the prospect of inflation, or a rapid rise in the prices of goods and services, is making him especially nervous. “We are particularly concerned about the nascent signs” of rising inflation in a variety of countries, he wrote. As a result, he added, money managers at Citadel, which runs a variety of hedge funds, are “carefully positioning” for a surprise, sharp upturn in inflation. Mr. Griffin added that he is also concerned about geopolitical risks, writing that his money managers need to be able to handle negative events if they do occur, “including a trade policy misstep or a military conflict.” He did not elaborate. In an interview with CNBC in November, Mr. Griffin said the stock market was in the “seventh inning” of a rally. He said through a spokesman on Monday that he still thinks there are several innings to go before a downturn begins and that he is more bearish on bond prices than stocks at the moment.