NEW DELHI/MUMBAI: The BSE Sensex fell more than 6 per cent on Monday as a rout in Chinese equities sparked widespread unrest in global financial markets.

Nifty also tanked 491 points to close at 7,809.

Here are 6 reasons why Sensex and Nifty are in a free fall:

1. Asia stocks at 3-year lows

Asian stocks dived to 3-year lows on Monday as a rout in Chinese equities gathered pace, hastening an exodus from riskier assets as fears of a China-led global economic slowdown roiled world markets.

Safe-haven government bonds and the yen rallied on the widespread unrest in the financial markets, set in motion nearly two weeks ago when China sharply devalued the yuan and stoked concerns about the state of its economy.

READ ALSO: Asia stocks plummet as China rout gathers pace

2. Global cues

Global stock markets are tumbling after a survey showed Chinese factory activity contracted at their fastest pace since the depth of the global financial crisis in 2009.

Fears of a China-led global economic slowdown drove Wall Street, previously seen as a safe-haven, to its steepest one-day drop in nearly four years on Friday. A 1.1 percent fall in S&P 500 mini futures suggested sentiment remained weak.

3. Rupee at lowest since September 2013

Rupee slumped to as low as 66.48 per dollar on Monday morning.

It is lowest since September 2013, as Asian markets reeled under fears of a China-led global economic slowdown.

4. Moody's lowers India's growth forecast to 7%

Fears over deficient rains in the current monsoon season and gradual progress of reforms have prompted global credit ratings agency Moody's to lower India's growth forecast for this year by 50 basis points to 7 percent.

READ ALSO: Moody's cuts India's 2015 growth forecast to around 7%

5. Sluggish exports

On the macro front, India's exports narrowed for the eighth straight month by 10.3 per cent in July to USD 23.13 billion, widening the trade deficit to USD 12.81 billion.

6. Falling oil prices

Brent and US crude oil futures hit fresh 6-1/2-year lows on Monday to drop below the latest supports of $45 a barrel and $40 a barrel each as investors fretted that a slowing Chinese economy will lead to weaker demand amid a global supply surplus.

(With inputs from agencies)

