NEW YORK (CNNMoney.com) -- The central bank of greatest concern to investors and U.S. businesses right now isn't the Federal Reserve. It's the People's Bank of China.
The Chinese central bank tightened credit Friday by requiring banks in China to increase their reserves for the second time this year. The move once again rattled markets around the globe.
By contrast, the exit strategy that Federal Reserve chairman Ben Bernanke laid out Wednesday detailing how he expected the Fed to start tightening credit in the U.S. caused barely a ripple.
"It's a global economy and it's becoming more and more global," said David Wyss, chief economist for Standard & Poor's. "You have to pay attention to what's happening in the world's No. 2 economy." (China is technically still #3 but is poised to pass Japan once Japan reports its 2009 gross domestic product this weekend.)
Kurt Karl, chief U.S. economist for Swiss Re, said the 8.7% economic growth in China last year is a major part of the reason the global recession likely ended in the middle of 2009.
Concerns about the fragility of that recovery, especially in light of debt problems dogging Europe right now, makes any slowing of Chinese growth a reason for concern everywhere.
"China has become a big part of the engine of growth. It's stabilized the global economy through this downturn," said Karl.
But Karl and Wyss both believe the markets overreacted a bit to Friday's tightening in China.
Karl said that even with these steps and more moves expected later this year to slow the Chinese economy and keep prices in check, his firm recently raised its GDP forecast to growth of 9.4% this year. By contrast, most economists are forecasting only about 3% growth in the United States this year.
Karl said Friday's sell-off is due more to the uncertainty about Chinese policy than worries about an actual slowdown there.
"What the Fed is doing is built into the market. They've been fairly transparent," said Karl. "But the Chinese are so opaque that whenever they make a move, the timing is a surprise."
Slower U.S. exports ahead. Wyss said the biggest impact of a slowdown in China on U.S. businesses would come from reduced demand for U.S. goods.
China bought nearly $70 billion of U.S. goods in 2009, making it the No. 3 destination for U.S. exports, behind only Canada and Mexico.
In addition, Wyss said China also helps the U.S. sell more throughout Asia because countries like Japan and South Korea benefit from China's growth. Pacific Rim countries bought nearly $200 billion in U.S. goods last year, nearly matching European demand for our exports.
"Japan and Korea came out of recession sooner than later because of their exports to China, and they are big buyers of our goods," Wyss said.
Beyond that, many U.S. companies have grown to depend on their Chinese operations for sales and profits. General Motors sold almost as many vehicles in China as in the United States last year, and the Chinese market was one of the battered automaker's few profitable operations.
Nonetheless, Wyss said the tightening in China will likely shave only about 0.1 percentage point off of U.S. economic growth this year, making it more of a slight breeze than a true headwind for the recovery in the U.S.
But Wyss agreed that the Chinese central bank is doing more to slow growth than Bernanke has, despite the Fed pulling back on some of its programs that have dumped trillions into the U.S. economy in recent years.