Mumbai, Sep 27 (IANS): Key Indian equity indices plunged over one per cent each during the mid-afternoon trade session on Wednesday, with the BSE Sensex shedding over 300 points and the NSE Nifty50 over 100 points.

According to market observers, caution ahead of futures and options (F&O) expiry, coupled with a weak rupee and profit booking in banking, healthcare and automobile stocks, hampered investors' risk-taking appetite.

Around 2.30 p.m., the wider 51-scrip Nifty of the National Stock Exchange (NSE) traded at 9,755 points -- down 116.50 points or 1.18 per cent, from its previous session's close.

The 30-scrip Sensitive Index (Sensex) of the BSE, which opened at 31,785.24 points, traded at 31,257.79 points -- down 341.97 points, or 1.08 per cent, from its previous day's close at 31,599.76 points.

The Sensex has so far touched a high of 31,797.46 points and a low of 31,223.33 points during intra-day trade.

The BSE market breadth was bearish -- with 1,840 declines and 592 advances.

On Tuesday, the benchmark indices closed marginally in the red on the back of continuous outflow of foreign funds and selling pressure in telecom, Teck (technology, media and entertainment) and FMCG stocks. However, some losses were pared by healthy buying in metals and realty stocks.

The Nifty closed at 9,871.50 points -- down 1.10 points or 0.01 per cent, while the Sensex closed at 31,599.76 points -- down 26.87 points, or 0.08 per cent.