Mid- and small-cap shares were outperforming their larger peers.The S-P BSE Sensex and NSE Nifty 50 indexes extended declines in afternooon deals ahead of the economic growth (GDP) data due to be presented by the government later in the day.

Weakness in heavyweights like Reliance Industries, ICICI Bank, HDFC, Tata Consultancy Services, Hindustan Unilever, Infosys and State Bank of India weighed on the benchmarks.

The Sensex fell as much as 466 points to hit an intraday low of 40,664.18 and the Nifty 50 index dropped 134 points to hit an intraday low of 12,017.40.As of 1:59 pm, the Sensex traded 408 points or 1 per cent lower at 40,722 and the Nifty 50 index was down 115 points or 0.95 per cent at 12,036.In a poll conducted by news agency Reuters, economists expect GDP growth to come in at 4.7 per cent in July-September, down from 5.0 per cent in the previous quarter and 7 per cent in the three-month period till September 30, 2018.Fifteen of 19 sector gauges compiled by BSE were trading lower led by the S-P BSE Metal and S-P BSE Energy indexes 1.3 per cent fall.

Auto, banking, oil - gas, capital goods, finance, information technology and FMCG shares were also witnessing selling pressure.On the other hand, S-P BSE Telecom index was up 2.6 per cent.Mid- and small-cap shares were outperforming their larger peers as the S-P BSE MidCap index fell 0.2 per cent while S-P BSE SmallCap index was up 0.13 per cent.In the Nifty 50 basket of shares, 44 were trading lower while only six were among the gainers.Dr.

Reddy's Labs was top loser in the Nifty 50 basket, down 2.6 per cent at Rs 2,899.

Hindustan Unilevr, Hindalco, State Bank of India, Yes Bank, Mahindra - Mahindra, Zee Entertainment, Tata Steel, Sun Pharma, Reliance Industries and Eicher Motors were also trading lower.On the flipside, Bharti Infratel, Adani Ports, Bharti airtel, NTPC and Coal India were among the notable gainers.The overall market breadth was negative as 1,330 shares were declining while 1,074 were advancing on the BSE.