The Bombay Stock Exchange (BSE) Sensex on Thursday fell by 145 points in volatile trade as investors squared up positions in derivatives ahead of the expiry of May contract amid weak global cues. Terming the roll over of positions to next series as normal, market players said operators and retail investors generally follow this process to avoid margin calls.
 The Sensex opened weak and gradually moved downward to the intra-day low of 14,174.05. It later ended at 14,218.11, a net fall of 145.15 points or 1.01 per cent from Wednesday’s close of 14,363.26.
The broader S&P CNX Nifty of the National Stock Exchange (NSE) dropped by 41.30 points or 0.97 per cent to close at 4,204.90 from previous close of 4,246.20.
Taking a cue from weakness in Asian markets, Foreign Institutional Investors (FIIs) and domestic funds resorted to selling pressure while operators were engaged in roll over of outstanding positions in derivatives.
Some brokers, however, attributed heavy selling pressure at the fag end of session to speculation that the NSE may impose extra margins on derivatives positions.