Thailand's economy and exports will grow less than expected this year because of U.S. tariffs, a leading business group said on Wednesday, adding the country could lose market share in the United States if a tariff reduction was not secured. Southeast Asia's second-largest economy was now expected to grow between 2.0% and 2.2% this year, down from a previous forecast of 2.4% to 2.9% growth, the Joint Standing Committee on Commerce, Industry and Banking said.