The number of real estate transactions in the Hamptons fell 21 percent during the second quarter, adding to evidence that the high end of the housing market is faltering.

Sales volume in these wealthy beach communities fell to 561 during the three-month period, from 706 in the second quarter last year, according to a report from Douglas Elliman Real Estate and Miller Samuel Real Estate Appraisers & Consultants. The average sale price also declined, slipping 0.3 percent to $1.68 million.