<p>The sensex, which had witnessed two big losses this month, tumbled 451.63 points to 16,403.30 points in the first ten minutes of trading.<br /><br />Similarly, the wide-based National Stock Exchange index Nifty dropped by 140.50 points to 4865.05 points.<br /><br />Brokers said the selling focus was more on banking and realty stocks after Dubai's debt problems revived concerns about the global financial system and rattled markets across Europe and Asia.</p>
<p>The sensex, which had witnessed two big losses this month, tumbled 451.63 points to 16,403.30 points in the first ten minutes of trading.<br /><br />Similarly, the wide-based National Stock Exchange index Nifty dropped by 140.50 points to 4865.05 points.<br /><br />Brokers said the selling focus was more on banking and realty stocks after Dubai's debt problems revived concerns about the global financial system and rattled markets across Europe and Asia.</p>
