By John S. McClenahen Initial claims for unemployment insurance resumed their decline last week, falling to 339,000, some 11,000 less than the previous week's revised figure of 350,000, the U.S. Labor Department reported July 22. The department's four-week moving average for initial jobless claims, which smoothes out week-to-week changes, also declined last week, down 2,500 from the previous week's figure to 336,750. The Conference Board's index of U.S. leading economic indicators, which previews the economy's short-term track, declined in June, its first decline since March 2003, the New York-based business research group reported on July 22. The leading index for June was 116.2, down two-tenths of a percentage point from May. "June's weakness was not widespread, and some of the decline was from the average manufacturing work week, which was most likely the result of many businesses being closed for President Reagan's funeral," said the Conference Board.