In what may be an indication of the weeks ahead, most of the Asia Pacific markets reversed Monday's gains in trading yesterday.
Fitch Ratings joined competitor Standard & Poor's in also downgrading Britain's credit rating on Monday, from "AA+'' to "AA'' with a negative outlook, meaning Fitch could further downgrade Britain's creditworthiness. Agency Moody's was also reported to be about to issue a downgrade.
The pound plunged a further 3.41% against the US dollar to $US1.32, following Friday's colossal 10% dive. At one point the pound struck its lowest level since 1985, at $US1.31, PA reported.
Against the euro, the pound was also down, falling 2.37% to 1.19.
Trading on Monday in Britain, Europe and the US saw declines in the major index, while in Asia Pacific the Shanghai Composite made a 1.5% gain, Japan's Topix was up 1.8%, the ASX 200 was up 0.5% and the NZX up 0.28%.
Yesterday, the continued uncertainty saw the New Zealand dollar hit a three-year high against the British pound, trading at 53.04p at noon.
Craigs Investment Partners broker Peter McIntyre said volatility in the Asia Pacific markets was likely to continue throughout the week.
"A lot of the sell-off has been the [British] banking sector, given it is the business centre of Europe,'' Mr McIntyre said.
While there had been "a chorus of economists'' saying they expected cuts to official cash rates, Mr McIntyre believed the main issue was more political than economic, given the resignation of Britain's Prime Minister David Cameron.
"Either way, there is a lot of uncertainty,'' he said.
Yesterday the NZX 50 closed up 0.44%. Other markets were still trading at the time, the ASX down 0.53%, Japan up 0.47% and the Shanghai Composite down 0.04%.
The British pound slumped to a 31-year low against the US dollar as turbulence in currency markets continued.
On Monday, European shares fell and banks made their biggest two-day loss on record as uncertainty continued to rock global markets, Reuters reported.
The pan-European STOXX 600 fell 4.1% after suffering a 7% drop, its biggest one-day fall since 2008, on Friday, the day after the referendum in which the UK voted to quit the EU.
Wall Street continued its slide, sending major US stock indexes to their worst two-day fall in about 10 months, AAP reported on Monday trading.
All three main indexes fell at least 1.5% on Monday, the referendum outcome having roiled global markets and led investors to seek safe-haven assets.
The Nasdaq dropped more than 2%, underperforming the other major indexes, amid fears that fallout from Britain's decision could hit business investment spending in the technology sector.
Tech, materials, financials and energy were the worst-performing sectors.
"The momentum has continued downward because there continues to be a lot of uncertainty,'' Eric Kuby, chief investment officer at North Star Investment Management, in Chicago, said.
"It's important to note that it's orderly. It doesn't feel panic-inspired.''
The Dow Jones industrial average fell 1.5% to 17,140.24, the S&P 500 was down 1.81% to 2,000.54 and the Nasdaq Composite dropped 2.41% to 4,594.44.
