The turmoil in Germany has pressured the euro, but bourses in Paris and Frankfurt were solidly higher. The US economic calendar is relatively quiet ahead of the Thanksgiving holiday aside from a handful of earnings, which were mixed.
Traders believe of Germany that "a worst-case scenario will not unfold, either because a political solution will be reached or because the ECB will do all that is necessary with its monetary policy to fill any confidence gaps," said Briefing.com analyst Patrick O'Hare.
About 15 minutes into trading, the Dow Jones Industrial Average stood at 23,569.31, up 0.6 percent.
The broad-based S&P 500 gained 0.5 percent to 2,596.08, while the tech-rich Nasdaq Composite Index advanced 0.8 percent to 6,842.82.
Time Warner rose 1.2 percent and AT&T edged up 0.1 percent a day after the Justice Department sued to block AT&T's proposed $85 billion takeover due to antitrust concerns.
The companies maintain the deal should go through because the proposed transaction is a "vertical" merger and AT&T and Time Warner do not directly compete.