The Dow Jones Industrial Average was trading near sessions lows Monday afternoon, with the blue-chip average down more than 500 points at its nadir. The Dow was most recently off 470 points, or 1.9%, at 23,638, with a downturn in shares of 3M Co. and Home Depot Inc. weighing on the price-weighted gauge. Only shares of UnitedHealth Group Inc. and McDonald’s Corp. were trading in positive territory. At its lows of the day, the Dow was down 526 points. Meanwhile, the S&P 500 index was down 2.4%, slipping below a technical level for the S&P 500 at 200-day moving average at 2,589.93, according to FactSet data. The Nasdaq Composite Index was off 2.8% at 6,869. Selling was driven in large part on technology and internet names, which have been contributing to weakness in the broader market since last week. Wall Street was closed for Good Friday at the end of last week and European markets are closed for Easter Monday.