LONDON • Problem loans at some of Standard Chartered's large clients may top US$600 million (S$851 million) as a string of corporate scandals coincides with woes at firms hit by the coronavirus pandemic. NMC Health, the hospital operator that has uncovered evidence of fraud, and Hin Leong Trading, the Singapore oil trader being investigated by police, represent nearly US$500 million of lending for Standard Chartered, according to public filings. Separately, a South African farm bank that the London-based company lends to has defaulted on some of its debt.