The stock market witnessed a significant downturn today. The 30-share BSE benchmark Sensex tanked 1,414.33 points, or 1.90 percent, to settle at 73,198.10. During the day, it plunged 1,471.16 points, or 1.97 percent, to 73,141.27. Extending losses to the eighth straight day, the NSE Nifty slumped 420.35 points, or 1.86 percent, to 22,124.70. Global oil benchmark Brent crude dipped 0.69 percent to USD 73.53 a barrel. The BSE Sensex eked out marginal gains of 10.31 points or 0.01 percent to settle at 74,612.43 on Thursday. The Nifty slipped 2.50 points, or 0.01 percent, to 22,545.05, registering its seventh day of decline.