The Bombay Stock Exchange benchmark Sensex dipped by 21 points in early trade today. This follows fresh selling in banking sector stocks after a hike in interest rates. The Sensex, which had lost 48 points in the previous session, fell to 17,440 points in the first five minutes of trading as some of the leading banking stocks declined. Similarly, the wide-based National Stock Exchange declined by 11.25 points to 5,225.85 points. On Friday, the RBI raised short-term lending and borrowing rates by 25 basis points to 5.50 per cent and 4 per cent.