The Sensex, which, tumbled to a low of 13,262, has recovered some what and is now down 377 points at 13,422.Tata Steel has plunged 7.5% to Rs 446. ACC and Reliance Communications have shed 6.5% each to Rs 1,035 and Rs 419, respectively.SBI has dropped 6.8% to Rs 1,262. ICICI Bank has slipped over 6% to Rs 823, and HDFC Bank has tumbled over 5% to Rs 1,030.Bharti Airtel and NTPC have declined 5.7% each to Rs 597 and Rs 143, respectively.Reliance Energy is down over 5% at Rs 526.Out of 2,505 stocks traded so far, 1,878 have declined, 578 have advanced and the rest are unchanged."Something has gone wrong. We are trying to figure out what it is," said a dealer in a domestic brokerage house.The weak sentiment was first felt in banking stocks in the wake of late Friday's Reserve Bank of India (RBI) decision to hike the cash reserve ratio (CRR) by 50 basis points in two stages. Slowly, the impact spread to other counters.Speculation that there could be huge unwinding of leveraged positions from big brokerage houses also did not help. The unwinding was seen mostly in banking stocks.Market players said there was also a talk of rogue trader Ketan Parekh making a huge selling on behalf of a big industrial house. The issue, however, could not be confirmed.