* World stock index set for first monthly rise since January
* Easing of tensions between North and South Korea buoys sentiment
* M&A activity keep stocks in spotlight (Updates with early U.S. markets activity, changes byline, dateline, previous LONDON)
By Caroline Valetkevitch
NEW YORK, April 30 (Reuters) - Global stock indexes were flat to slightly higher after upbeat earnings and deal news on Monday, while the U.S. Treasury yield curve flattened for a third straight session after U.S. economic data missed expectations.
MSCI's all-country index of global equities was up 0.02 percent on the day, on track for a gain for April, its first positive month since January.
Starting off another busy week for first-quarter earnings, McDonald's reported a better-than-expected rise in sales and its shares jumped 5.6 percent. Apple is set to report on Tuesday.
"If the previous several weeks of earnings season are any indication, corporate results should continue to act as a buffer to any meaningful turn lower in equity markets," said Peter Kenney, senior market strategist at Global Markets Advisory Group in New York.
Reports of big M&A deals, including U.S.-based Marathon Petroleum's agreement to buy Andeavor, T-Mobile US's proposed merger with Sprint Corp and a tie-up between British supermarket chains Sainsbury's and Walmart's ASDA, kept global stock markets firmly in the spotlight.
The Dow Jones Industrial Average rose 66.28 points, or 0.27 percent, to 24,377.47, the S&P 500 lost 3.43 points, or 0.13 percent, to 2,666.48 and the Nasdaq Composite dropped 20.39 points, or 0.29 percent, to 7,099.41.
The pan-European FTSEurofirst 300 index rose 0.18 percent.
Friday's seemingly successful summit between the leaders of North and South Korean added to positive market sentiment.
In the U.S. bond market, the yield gap between U.S. 5-year notes and U.S. 30-year bonds narrowed to 27.20 basis points , the lowest spread in more than six years.
Data showed U.S. personal income rose just 0.3 percent in March, compared with expectations of 0.4 percent. On the consumption side, personal spending in February was revised lower to a rise of 0.3 percent, instead of the previously reported 0.4 percent increase.
Benchmark 10-year Treasury notes last rose 3/32 in price to yield 2.9475 percent, from 2.957 percent late on Friday.
Weaker-than-expected German data hurt the euro against the U.S. dollar.
German monthly retail sales unexpectedly dropped in March, dampening cheer around a consumer-led upswing in Europe's biggest economy. Regional data showed annual inflation in four German states steady in April.
The dollar index rose 0.35 percent, with the euro down 0.47 percent to $1.2071.
The Federal Reserve is also due to meet this week, and while no rate hike in benchmark U.S. interest rates is expected, investors will look for clues on the future pace of increases.
U.S. crude rose 0.07 percent to $68.15 per barrel and Brent was last at $74.23, up 0.6 percent.
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Additional reporting by Karen Brettell in New York, Abhinav Ramnarayan in London, and Sruthi Shankar in Bengaluru; editing by Catherine Evans and James Dalgleish