The BSE benchmark Sensex tumbled over 440 points and the NSE Nifty cracked below the key 15,000-level in early trade on Friday in line with a slump in other Asian markets as US bond market turmoil continued to fan investor worries globally.

The BSE gauge Sensex was trading at 50,405.99, showing a drop of 440.09 points or 0.87 per cent in the opening session.

Similarly, the NSE barometer Nifty was quoted lower by 124.75 points or 0.83 per cent at 14,956.

On the Sensex chart, IndusInd Bank, ICICI Bank, SBI, PowerGrid and HDFC Bank emerged as major laggards -- dropping as much as 3 per cent.

Of the Sensex shares, 21 traded in the red.

Elsewhere in Asia, equity markets continued their decline on Friday following a retreat on Wall Street amid concerns over rising yields in bond markets.

"The 'bond bears vs equity bulls' game continues in the US market with similar reverberations in other developed and emerging markets. The highly valued Nasdaq appears to be in a short-phase of reversion to mean, having declined 10 per cent from record highs.

"The US 10-year yield has again spiked to 1.575 per cent giving further ammunition to bond bears," said V K Vijayakumar, Chief Investment Strategist at Geojit Financial Services.

Back home, both Foreign institutional investors (FIIs) and Domestic institutional investors (DIIs) turned sellers on Thursday, impacting market sentiments, he added.

On Thursday, the Sensex had shed 598.57 points or 1.16 per cent, and the Nifty had lost 164.85 points or 1.08 per cent.

Foreign investors had offloaded equities worth Rs 223.11 crore on a net basis in Indian capital markets on Thursday, according to exchange data.

Meanwhile, global crude oil benchmark Brent was trading 0.77 per cent higher at USD 64.32 per barrel.