New York - US stocks pushed higher on Tuesday, sending the Dow Jones Industrial Average and the S&P 500 to their best levels in more than five years.
US markets kept alive a rally in Europe, where shares rose in all the main exchanges helped by news of soaring investor sentiment in Germany.
Also sparking trade were reports of another possible big merger, of office supply retailers Office Depot and OfficeMax.
The Dow finished up 53.91 points at 14,035.67, its best level since October 12, 2007.
The broad-based S&P 500 rose 11.15 points to 1,530.94 - its highest level since October 31, 2007 - and the tech-rich Nasdaq Composite increased 21.56 to 3,213.59.
Fresh merger-and-acquisition reports after last week's big merger of American Airlines and US Airways, and the Berkshire Hathaway-3G Capital takeover of Heinz, gave a spark to trade.
Office Depot gained 9.4%, Office Max 20.1%, on news that they are exploring an all-stock merger, while powerful rival Staples jumped 13.1%.
Health-care shares slumped, led by Humana, after news that government-run Medicare said it would cut payments more sharply than expected to insurers for certain services.
Humana dropped 6.4%, Universal Healthcare fell 4.6%, and national Health Partners lost 5.0%.
The Dow was led by a 2.2% gain from Cisco and 2.0% advance from General Electric.
Google, despite facing a new challenge from Microsoft on the email side of the business, topped the $800 level for the first time, adding 1.8% to end at $806.84.
Bond prices slipped. The yield on the 10-year Treasury bond rose to 2.03% from 2.01% late on Friday, while the 30-year was rose to 3.20% from 3.18%. Bond prices and yields move inversely.