Falling for the fifth day in a row on Monday, equity benchmark BSE Sensex tumbled over 1 per cent to drop below the crucial 75,000 level, tracking a US market trend and unabated foreign fund outflows amid concerns over US tariffs.The 30-share BSE benchmark tanked 856.65 points or 1.14 per cent to settle at 74,454.41.During the day, it plummeted 923.62 points or 1.22 per cent to 74,387.44.