United States Sales of previously occupied homes rose modestly from April to May, the third monthly increase this year, but signs of a housing recovery are fragile at best.

The U.S. National Association of Realtors said Tuesday that home sales rose 2.4 per cent last month to a seasonally adjusted annual rate of 4.77 million, from a downwardly revised pace of 4.66 million in April.

About one out of every three homes sold was a foreclosure or distressed sale. That helped drag down the median price to $173,000 — 16.8 per cent below a year ago. Falling prices coupled with new rules for property appraisers have caused many transactions to fall apart or be delayed.

“We have just been flooded with emails, telephone calls on the appraisal problems,” said Lawrence Yun, the Realtors’ chief economist.

The sales results missed economists’ expectations, and stock markets headed lower on the news.