* Asian stock markets : tmsnrt.rs/2zpUAr4
* MSCI ex-Japan near 18-mth highs, up nearly 5% this month
* E-mini futures at all-time highs, up 2.7% this month
* Currencies tread water, Sterling near 3-week lows
By Swati Pandey
SYDNEY, Dec 23 (Reuters) - Asian markets idled near 18-month highs on Monday as volumes weakened ahead of the Christmas holiday break and investors squared off their positions, taking home hefty gains made earlier this month.
MSCI's broadest index of Asia-Pacific shares outside Japan was steady after rising 1.4% last week and over 5% this month. For the final quarter of the year, the index is up nearly 10% so far.
Japan's Nikkei climbed 0.1% after reaching a 14-month top last week. It was ahead by 2.3% for the month so far. South Korea's market was a shade weaker after adding 5.5% so far in December.
Chinese shares were slightly lower with the blue-chip CSI300 down 0.1%.
E-Mini futures for the S&P 500 held at all-time highs having put on 2.7% for the month.
Global stocks were "basking in the after-glow of the U.S. China trade deal and continued encouraging signs of stabilisation in the global growth slowdown," said David Bassanese, Sydney-based chief economist at Betashares.
On Friday, the benchmark S&P 500 extended its run of record highs to seven straight sessions, its longest streak in more than two years. All three major U.S. indexes - the S&P 500, Nasdaq and Dow - notched up gains.
"While we're entering 2020 with more hope than last year, as is always the case, there's never any room for complacency," Bassanese added.
Data on Friday showed U.S. growth nudged up in the third quarter, while there were signs the economy maintained its moderate pace of expansion as the year ended. Consumer spending was stronger than previously reported, and there were upgrades to business spending.
U.S. President Donald Trump gave markets more reasons to cheer on Saturday when he said the United States and China would "very shortly" sign their so-called Phase One trade pact.
Under the deal, the United States would agree to reduce some tariffs in exchange for a big jump in Chinese purchases of American farm products.
The only major data this week is the U.S. personal consumption expenditure (PCE) deflator for November, due on Friday.
Data elsewhere reminded investors of potential weak spots in the world economy.
The mood among German consumers deteriorated unexpectedly heading into January, a survey showed, suggesting that household spending in Europe's largest economy could weaken at the beginning of next year.
The euro held at $1.1077 after slipping 0.4% last week.
Sterling last fetched $1.3009, not far from Friday's three-week low of $1.2976. It slid 2.6% last week for its worst weekly showing since October 2017.
The safe haven Japanese yen was treading water at 109.40.
That left the dollar index barely changed at 97.678 against six major currencies.
In commodities, Brent crude was off 17 cents at $65.97 a barrel, while West Texas Intermediate crude slipped 14 cents to $60.3 a barrel.
Spot gold was slightly ahead at $1,479.30 an ounce.
Reporting by Swati Pandey; editing by Richard Pullin