Mumbai, Aug 8 (PTI) Benchmark Sensex slumped 260 points while the Nifty cracked below the 10,000-mark today after Sebi clamped down on 331 suspected shell companies listed on exchanges. The 30-share Sensex, which lost nearly 52 points in the previous session, resumed higher at 32,341.05 and advanced to 32,354.77 in early trade. But selling pressure suddenly emerged and dragged the gauge below the 32,000-mark briefly to a low of 31,915.20, ...