South Korea's top credit appraisers are found to be granting inflated ratings for bonds issued by local firms, data showed Monday, sparking concern for their trustworthiness. Three local appraisers -- Korea Ratings Co., NICE Investors Service Co. and Korea Investors Service Co. -- have granted top ratings of between "AAA" and "A" on 78.9 percent of corporate bonds floated here as of Friday, market data showed.