U.S. stocks closed in the green areas as the ECB started its €1tn quantitative easing program on Monday.
The ECB said last week the purchases will amount to 60 billion euros each month, while may extend its bond purchases beyond September 2016, if required.
The generous stimulus plans announced by major central banks have bolstered equity markets, especially in the United States.
Data released on Friday also gave positive outlook about the world’s biggest economy, yet raise speculations the Fed may raise its borrowing cost by the middle of 2015.
The NASDAQ composite index, which rose above 5,000 points for the first time in 15 years last week, was up 0.31% to close at 4,942.44 points.
Apple Inc announced its smartwatch on Monday coming in various models, including a one with sapphire faces costing up to $17,000.
Apple shares edged up 0.54 points or 0.43 percent to close at $127.14.
Standard & Poor's 500 rose 0.39% to close at 2,079.43 points, while the Dow Jones industrial average index added 0.78% to 17,995.72 points.