Luxury brands feel the heat

"We believe that our exposure is limited and manageable, and do not expect that the devaluation will have a material impact on the company's financial performance," GM said in a statement on Tuesday. Building vehicles for sale in each of its main markets creates "a natural hedge", the company said.

For industrial companies, the devaluation is another headwind on earnings, piling onto slow global growth, lower oil & gas investment and sluggish consumer demand.

"It's a cumulative effect in an already difficult environment," said Karen Ubelhart, an analyst with Bloomberg Intelligence. Emerson Electric Co, mining equipment maker Joy Global Inc and engine producer Cummins Inc have among the highest sales attributed to China, she said.

Kone Oyj, the Finnish elevator maker that got more than one-third of sales from China in the second quarter had a month ago surprised investors by raising its full-year profit forecast while saying the Chinese market may remain stable this year even as the pace of new construction slumps.

"Given that we operate locally in China, the impact of yuan devaluation is not significant for us," Eriikka S?derstr?m, chief financial officer at Kone, said on Tuesday in an e-mail. "There has been plenty of volatility in the foreign exchange market this year, and compared with that, this is a small correction."

For technology companies, the devaluation can cut both ways. The nation is both the largest electronics manufacturing hub and the largest consumer of personal computers and mobile phones. China Mobile Ltd has more than twice as many phone-service subscribers as the US has.

That means the policy shift can either deliver growth or bring it to a halt for a varied group of suppliers like chipmakers Intel Corp and Qualcomm Inc, which get more than half its sales from China.

"There is a big difference between products that are intended to be sold and stay in China versus those that are just manufactured globally," said Christopher Rolland, an analyst at FBR Capital Markets & Co.

Some Taiwan companies may benefit from the improved profit margins. Apple Inc suppliers Hon Hai Precision Industry Co and Pegatron Corp, for example, both pay a major share of their workforce in yuan and sell in US dollars.

Whatever the consequences for now, the important result may be if the devaluation eventually stimulates growth. "If this is part of getting China's economy going again, that would help," analyst Ubelhart said. "But that is not current. That is more of a second effect."