NEW YORK, New York - U.S. stocks retreated from record levels on Monday following remarks by Federal Reserve Chair Jerome Powell that challenging times lay ahead. The tech-heavy Nasdaq Composite tumbled 215.50 points, or 0.95 percent, to settle at 22,573.47. The Dow Jones Industrial Average showed relative resilience but still finished in negative territory, dipping 88.76 points, or 0.19 percent, to 46,292.78. The selling pressure in the U.S. extended north of the border, with Canada's S&P/TSX Composite index dropping 143.35 points, a loss of 0.48 percent, to end the session at 29,815.63. Mainland China's SSE Composite Index slipped 0.18 percent to 3,821.83.