Global markets sagged Thursday as uncertainty over trade relations between the United States and China continued to sour investors. The Dow Jones industrial average plunged 448 points at its low before clawing back late in the day to finish at a loss of 286 points, or 1.11 percent, driving it into negative territory for the week. If the Dow were to finish in the red for the week, it would be the fifth week in a row and the first such slump in eight years. Technology continued to sink the blue chips as President Trump ratcheted up pressure on Chinese tech firms. United Technologies and IBM led the Dow Jones downward. Energy was hit by a steep drop in oil prices, dragging Exxon Mobil and Chevron with it. Energy, technology, industrials, and financials were the biggest losers of 11 sectors. Utilities and real estate were the only gainers on the day. The trade tensions have stymied global growth, resulting in a considerable pullback in corporate earnings estimates for all of 2019. ‘‘The market is adapting to the fact that we are looking at much lower growth estimates,’’ said Chase Hinderstein, portfolio manager with The Wise Investor Group in Reston, Va. ‘‘Earnings estimates for the S&P have been reduced tremendously, to 3.2 percent for this year compared to estimates of 7 percent at the beginning of 2019 and 10 percent last September.’’ Shares of Facebook, Amazon, Apple, Netflix, and Google-parent Alphabet tumbled as more companies said they would abide by the restrictions against Huawei. Apple depends on China for a significant amount of its revenue.