Retail spending in the US gained 0.6 percent in March, rising to $494.6 billion, overshooting economists' expectations and marking the biggest gain since November.

Analysts also said investors were reassured after weekend strikes by Britain, France and the US on Syria did not spur major retaliation from Syria's allies Iran and Russia.

About 10 minutes into trading, the Dow Jones Industrial Average was up 0.7 percent to 24,524.36.

The broad-based S&P 500 gained 0.5 percent to 2,669.37, while the tech-rich Nasdaq Composite Index advanced 0.4 percent to 7,138.07.

Money managers remain optimistic about first-quarter earnings, which are expected to show a 17.3 percent jump for S&P 500 companies compared with the year-ago period.

In spite of those rosy forecasts, a key question is whether the market will push higher following earnings, or whether good results are already baked into valuations. On Friday, major banks fell sharply despite reporting good profits.

Bank of America edged up 0.2 percent after reporting Monday its 34.2 percent jump in first-quarter profits to $6.5 billion behind a strong performance in key businesses thanks in part to a lift from higher interest rates.

Dow member Merck shot up 3.3 percent after reporting successful clinical results for its Keytruda treatment for lung cancer.