U.S. diversified stock funds lost ground in the latest week, ending a three-week winning streak. They lost 0.42% on average in the week ended May 28, cutting their year-to-date gain to 4.18%, according to Lipper Inc. data. In a holiday-shortened week, the market lost ground three of the four days. Investors were worried by stock market news of soft U.S. economic data and the June 5 debt-payment deadline for Greece.