Wall Street eked out gains as merger and takeover activity outweighed concern about rising oil prices and escalating chaos in Iraq and an IMF downgrade in its US economic growth forecast.
In the final hour of trading in New York, the Dow Jones Industrial Average rose 0.05 percent, the Standard & Poor's 500 Index added 0.09 percent, while the Nasdaq Composite Index gained 0.17 percent.
In the Dow, gains in shares of Chevron, up 1.2 percent, and those of Home Depot, up 1.1 percent, outweighed declines in shares of UnitedHealth, down 1.2 percent, and those of General Electric, down 0.9 percent.
The International Monetary Fund downgraded its outlook for the US economy, lowering its 2014 prediction to 2 percent because of harsh winter weather, from a 2.8 percent forecast in April. It maintained its 2015 forecast for 3 percent growth.
"Job growth has been healthy but labour markets are weaker than is implied by the headline unemployment number: long-term unemployment is high, labour force participation is well below what can be explained by demographic factors, and wages are stagnant," the IMF said in a statement. "With better growth prospects, the US should see steady progress in job creation."
"However, headline unemployment is expected to decline only slowly-in part because improving prospects will draw discouraged workers back into the labour force-and long-term unemployment will take time to fall to historic levels," according to the IMF.
Separate reports on Monday showed that US factory production rose 0.6 percent in May, compared with a 0.1 percent decline in April, which was less than previously thought, while the New York Fed's Empire State business conditions index posted its highest reading in four years in June.
US shares of Dublin-based Covidien jumped, last up 20.7 percent, after Medtronic agreed to buy Covidien for US$42.9 billion as part of a move to relocate its executive headquarters to Ireland from the US to take advantage of lower tax rates. Shares of Medtronic fell 1.4 percent.
Shares of Williams soared, last up 6.9 percent, after the company agreed to acquire control of Access Midstream Partners for US$6 billion with plans to merge the companies.
"The M&A absolutely keeps on coming," Ken Polcari, director of the NYSE floor division at O'Neil Securities in New York, told Reuters. "It's ripe for it with rates so low, all this money on the balance sheet and companies looking to grow their businesses."
Even so, gains were limited as oil prices continued their climb on concern about the potential for supply disruption from Iraq. Brent for August settlement rose as much as 0.7 percent to US$113.28 a barrel on the London-based ICE Futures Europe exchange, according to Bloomberg News.
Shares Yahoo! sank, last down 5.2 percent, after Alibaba Group posted disappointing revenue.
"Alibaba's numbers look as if revenue growth is slowing down and margins are lower than expected," Sameet Sinha, an analyst at B Riley & Co, told Bloomberg News. "Their mobile as a percentage of total transaction value has increased dramatically, and people tend to spend less on mobile."
In Europe, the Stoxx 600 Index ended the day with a 0.5 percent drop from the previous close. The UK's FTSE 100 and Germany's DAX each slid 0.3 percent, while France's CAC 40 slumped 0.7 percent.