Asian stock market indices were trading lower on Monday (5 December) as the euro declined to a 20-month low following a referendum held in Italy to amend its constitution.

Italian Prime Minister Matteo Renzi announced his resignation soon after he was defeated in the vote, which could lead eurozone's third largest economy into political chaos.

Voters were asked whether they supported changes to the constitution, and reform of the composition and powers of the Italian Parliament as well as the division of powers between the state, the regions and administrative entities. The bill was put forth by Renzi and his centre-left Democratic Party.

As voters rejected the referendum, the euro declined to new lows as investors, who are still recovering from the UK's decision to leave the EU, now fear that Italy's already troubled banking system could further destabilise.

"The 'no' vote was priced in to a certain extent in advance. So I do not expect a freefall in the euro in the near term...But in the long run, this will delay progress in Italy's efforts to get rid of banks' bad debt and is likely to widen the yield spread of German Bunts and the Italian bonds," Minori Uchida, chief currency analyst at the Bank of Tokyo-Mitsubishi, was quoted as saying by Reuters.

Indices in the region were trading as follows at 3.53am GMT:

CountryIndexPriceUp/Down%Change
Hong KongHang Seng Index22,489.02Down0.34%
JapanNikkei 22518,302.22Down0.67%
South KoreaKOSPI1,966.09Down0.23%
IndiaBSE26,217.37Down0.05%
AustraliaS&P/ASX 2005,395.90Down0.88%

On 2 December, the FTSE 100 closed 0.33% lower at 6,730.72, while the S&P 500 Index closed 0.04% higher at 2,191.95.

Among commodities, oil prices which surged last week – over the Opec oil output deal – was trading in the red. As of 3.59am GMT, WTI crude oil was trading lower by 0.91% at $51.21 (£40.34) a barrel, while Brent crude was trading 0.84% lower at $54 a barrel.