U.S. stock markets swung into the black in late trading today, with the Dow Jones Industrial Average (DJINDICES:^DJI) up 0.16% and the S&P 500 (SNPINDEX:^GSPC) gaining 0.33% as of 3:15 p.m. EST. In early trading, news of stiffer requirements for home buyers in China had stocks sinking, and it's still holding some stocks back. Chinese officials said they would require higher down payments and mortgage rates on second homes. They'll even tax profits on second homes at 20% in an effort to slow down real-estate speculation.

The news has shares of Alcoa (NYSE:AA) and Caterpillar (NYSE:CAT) down 1.4% and 1.9%, respectively. Both companies rely on growth in China for demand, and there's a bit of worry that growth may slow in 2013. I don't think curbs on second homes will have a huge impact on growth in China. They may actually keep the market from overheating like the U.S. market did a few years ago. There's no reason for long-term investors to sell on today's news, even if traders are fretting about China today.

Fear over China's economic growth also pushed oil below $90 per barrel for a period today. China is now the world's No. 1 importer of oil, so if Chinese growth slows, it will be bad for the oil trade.

On the positive side, shares of Wal-Mart (NYSE:WMT) pulled the Dow higher, gaining 1.9% today. Walmart Foundation president Sylvia Mathews Burwell was chosen as the new head of the Office of Management and Budget by President Obama today. The company also announced plans to install 4.7 MW of solar power in Ohio, which would make it the state's largest solar-power generator. Wal-Mart is one of the country's largest owners of commercial solar, which is a great revenue generator given the availability of rooftop space.