NEW YORK (TheStreet) -- Greece's problems could soon be felt in the United States.

"If Greece's creditors cut its debt, I think you're going to see other countries that have had similar trouble, asking for the same type of concessions," said Ian Winer, head of equity trading at Los Angeles, Calif-based Wedbush Securities, referring to Portugal, Italy and Spain, which face debt crises of their own. "That means the dollar is going to get a lot stronger and that's not good for U.S. multinationals and will result in lower earnings."

Greece is asking European creditors for a $59.4 billion bailout, in exchange for spending cuts and other reforms that were previously rejected by Greek voters in a historic referendum held July 5.

On Friday, the euro gained almost 1% against the dollar, but is still down 8.5% since the start of the year.

Meanwhile, the outlook for corporate earnings isn't looking bright. Second quarter earnings are expected to post a 4.4% year-over-year decline, according to FactSet. On March 31, analysts expected earnings to fall just 2.2%.

Still, Winer thinks Greece's troubles are just a hiccup for markets. He is more concerned about China.

China's Shanghai Composite Index is down 25% from its June 12 peak. The declines were even more dramatic, prior to Friday's 4.5% rebound and Thursday's 6% advance.

The selloff was sparked after too many investors bought stocks on margin. After all, the index is up 95% over the past year.

To stop the bleeding, Chinese officials suspended trading on about 50% of stocks and banned larger shareholders from selling stock for six months.

"I think the bigger question is what does this mean for the psychology of the Chinese consumer?" Winer added. "The consumer is ultimately going to drive a lot of the multinational corporations in the U.S. market."

U.S. companies like Apple (AAPL - Get Report) dropped 1.4% this week amid the volatility in China. Apple has plenty of exposure to the region. In 2014, 16% of Apple's net sales came from China, according to its annual report.