GLOBAL MARKETS-Asian shares fall to 2-wk low; Nikkei bucks trend
* Asia ex-Japan shares head for first loss in four days
* Dollar reverses losses against yen
* Australian dollar bounces after RBA rate cut
TOKYO, Aug 6 (Reuters) - Asian shares fell to a two-week low on Tuesday, with Japan a notable exception as it reversed early losses, while the Australian dollar pushed away from a three-year trough after the central bank cut official rates to a record low.
Japanese stocks rose more than 2.5 percent from their lows to end up 1 percent on talk the central bank was buying exchange-traded funds and a Reuters report a massive public pension fund was considering increasing its allocation mix to buy more stocks.
The turnaround in the Nikkei sparked shortcovering by options sellers and helped the dollar reverse early declines against the yen, both of which in turn reinforced the rise in the stock market.
European shares were expected to open lower, with Britain's FTSE 100 seen down as much as 0.4 percent and Germany's DAX down as much as 0.2 percent, while the U.S. S&P 500 index futures dipped 0.2 percent.
The Australian dollar rose to $0.8978, up 0.4 percent on the day, after the Reserve Bank of Australia cut its cash rate by a quarter point to 2.5 percent, as expected, but did not provide a clear signal that it may cut again.
The Aussie had hit a three-year low below 89 U.S. cents on Monday.
"It's as the market expected, although there's a little bit of disappointment that there wasn't a 50 point rate cut," said Brian Redican, senior economist at Macquarie Bank.
The U.S. dollar was up 0.2 percent at 98.415 yen, after the recovery in the Nikkei sparked yen selling.
The dollar had been weakening since Friday after a soft jobs report saw markets temper expectations the Federal Reserve could start scaling back its $85 billion-a-month bond-buying programme in September.
VOLATILE TOKYO MARKET
Japan's Nikkei advanced 1 percent after dropping as much as 1.6 percent earlier. The Nikkei is up 39 percent this year, driven by massive stimulus policies of the government and central bank.
Tokyo traders suspected the Bank of Japan bought exchange-traded funds to support the market. When the broader Topix index falls more than 1 percent in the morning session, the BOJ typically buys exchange-traded funds in the afternoon.
Volatility has increased sharply for the Japanese market since May 23, when the Nikkei plunged 7.3 percent after hitting a 5-1/2 year high during the day.
Since then, there have been 28 sessions where intraday swings exceeded 2.5 percent, compared with 16 for the year up to May 22 and four such days in the whole of 2012. The S&P 500 only has had 2 such trading days in 2013, and the Euro STOXX 50 has 15.
The Bank of Japan starts a two-day policy meeting on Wednesday. It is not expected to make any changes to its stimulus measures designed to spark inflation. 1/2ID:nL4N0G6041 3/8
ASIAN SHARES DOWN
Asian shares measured by MSCI Asia-Pacific ex-Japan fell 0.5 percent and were heading for their biggest one-day fall in one week.
Hong Kong's Hang Seng underperformed, losing 1.2 percent on the back of a 4.8 percent fall in index heavyweight HSBC after it posted lower-than-expected earnings.
"HSBC is taking everybody down with it today," said Linus Yip, a strategist with First Shanghai Securities. "Yes, their earnings may have missed, but HSBC shares had also jumped quite a fair bit leading into their earnings announcement."
In commodity markets, copper added 0.1 percent to around $6,980 a tonne after a 0.4 percent decline on Monday, while gold fell 1 percent, extending a 0.6 percent drop in the previous session to be not far from a two-week low of $1,282.69 hit on Friday.
Brent crude prices dipped 0.2 percent to around $108.50 a barrel, extending a 0.3 percent fall on Monday and heading for a third straight day of losses - which would be its longest losing run since late May.