A new study shows that small businesses are hurt the most, on a per worker basis, by internal fraud. In general, U.S. businesses lose an average of $9 per worker per day to employee theft—a total of $400 billion annually, according to the Association of Certified Fraud Examiners. And per-fraud losses at small businesses (under 100 workers) are nearly identical to those at the largest companies. Fraud experts say the most frequent culprit is a trusted employee whose money handling is not double-checked. A recent survey found that 48 percent of employees admitted to one or more illegal or unethical acts during the past year.