Mumbai, Dec 15 (IANS): India's key equity indices -- S&P BSE Sensex and NSE Nifty50 -- fell for the fourth consecutive session on Wednesday due to FII outflows on the back of the ongoing US Fed meet.

Besides, rising global concern over Omicron as well as a spike in inflation rate dampened investors' sentiments.

Notably, the FIIs sold stocks worth Rs 3,407.04 crore on the BSE, the NSE and the MSEI in the capital market segment.

The US Fed meet is being held from December 14-15. Any decision on the future hike in the US interest rates will drive away more foreign portfolio investors (FPIs) from the emerging markets, such as India.

In the day's trade, equity markets opened flat on mixed global cues and remained in the negative zone through the day.

Globally, Asian stock markets ended on a mixed note on Wednesday.

However, European shares inched higher on Wednesday ahead of the US Federal Reserve's policy decision that is likely to signal a quicker withdrawal of its pandemic stimulus measures to counter the broadening inflationary risks.

On the domestic front, realty, metals, and IT indices fell the most, whereas capital goods and auto indices gained the most.

The S&P BSE Sensex closed at 57,788.03 points, down 0.57 per cent from its previous close. The broader 50-scrip Nifty at the National Stock Exchange (NSE) ended the day's trade at 17,221.40 points, down 0.60 per cent from its previous close.

"Nifty closed down after a promising morning session, selling off ahead of the crucial US Fed meet later in the day," said Deepak Jasani, Head of Retail Research, HDFC Securities.

"In the process it closed below the upgap created on December 8 and nullified the effect of the near doji formation on the previous day," he added.

According to Siddhartha Khemka, Head of Retail Research, Motilal Oswal Financial Services: "Overall, the market is expected to remain in consolidative mode ahead of key central bank outcome and lack of positive triggers. Also, the covid situation took an ugly turn after the UK reported world's first death due to Omicron virus on Tuesday, which led to increase in global cautiousness.

"Investors are awaiting the outcome from the US fed meeting and looking for cues as to when the central bank plans to start interest rate hike apart from the pace of stimulus tapering."