* Euro eases from 6-month high vs dollar, 1-year high vs yen
* Dollar index rises above 6-month low plumbed earlier
* Euro prospects brighten after Macron's victory in France (Adds comment, updates prices)
By Gertrude Chavez-Dreyfuss
NEW YORK, May 8 (Reuters) - The euro fell from six-month highs against the dollar on Monday after Emmanuel Macron's victory in France's presidential election, as investors took profit on a roughly 3 percent gain for the currency since he won the first round two weeks ago.
Macron's overwhelming win on Sunday briefly pushed the euro above $1.10 against the greenback, the highest since the U.S. presidential election in November.
"A Macron win is largely priced into the euro," said Shaun Osborne, chief FX strategist at Scotiabank in Toronto. "Heavy trading in the spot market so far today suggests a modest unwind of the April and May rally is coming, at least."
The safe-haven yen and Swiss franc, meanwhile, fell on Monday as risk appetite improved with Macron's victory.
The French centrist's defeat of nationalist Marine Le Pen spelled relief for investors who had feared another populist upheaval after Britain's vote to exit the European Union and Donald Trump's shock election as U.S. president.
The euro rose as high as $1.1023, a six-month peak. It also jumped to a one-year high of 124.58 yen.
But by late trading in New York, the euro fell 0.6 percent to $1.0932 against the dollar, and 0.4 percent against the yen to 123.56 yen.
Removal of the political risk investors had associated with Le Pen - who had promised to take France out of the euro - prompted investors to refocus on economic fundamentals and the pace of monetary policy normalization in Europe and the United States.
Short positions on the euro also reached their lowest level since early May 2014 in the week up to last Tuesday, suggesting increased optimism for the currency, data showed on Friday.
But some analysts said that despite improving prospects in the euro zone, threats to the euro have not faded.
"Macron and his new En Marche! movement will need to gain considerable support within the French government in order to further his pro-euro agenda," said James Chen, head of research at Forex.com in Bedminster, New Jersey.
This would not be an easy task as Le Pen promised to continue her cause under a newly transformed far-right party that would run in next month's pivotal parliamentary elections, Chen added.
The dollar index, which tracks the U.S. currency against six rivals, added 0.4 percent to 99.067.
The greenback also rose to a three-week high against the Swiss franc and was last up 1.1 percent at 0.9983 franc. It gained 0.2 percent against the yen to 113.06.
Additional reporting by Ritvik Carvalho in London; Editing by Dan Grebler