Sensex fell by nearly 33 points in opening trade today after a seven-day gaining streak at 19,469. The wide-based National Stock Exchange, Nifty index also slipped by 17.40 points to 5,845. According to market analysts, oil and gas, IT and metal stocks were under pressure at prevailing levels. Reserve Bank's first-ever mid- quarter monetary policy review is to be announced later in the day.A weak trend in Asian markets also contributed to the negative sentiment, they said. Hong Kong's Hang Seng index was trading lower by 0.15 per cent in early trade today, while Japan's Nikkei was up 1.02 per cent.