There’s a blind spot in U.S. regulators’ oversight of audit firms--and it could mean investors in companies like Walmart Inc., Pfizer Inc. and 3M Co. are vulnerable.
Big Four accounting firms use their Chinese and Hong Kong affiliates to do significant work on the yearly audits of dozens of U.S. companies doing business in China, including Walmart, Pfizer and 3M, according to regulatory disclosures the auditors recently made for the first time.
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