Domestic auto sales fell sharply in late June to a rate 11.8 percent below that of a year ago, the major auto makers reported yesterday.

The drop caused sales for all of June to settle at 3.2 percent below the year-ago rate. That led market analysts to conclude that U.S. car makers may have trouble this summer holding on to the brisk sales they've enjoyed for nearly two years.

Industry leader General Motors Corp. finished the month poorly, with sales off 15 percent in the last 10-day period, causing its sales for the month to finish 5.7 percent down from a year ago. GM also suffered a drop in its market-share lead, losing ground to No. 2 Ford Motor Co. and No. 3 Chrysler Corp.

Ford sales were down 8.1 percent in the June 21 to 30 reporting period, finishing the month up 1 percent. Chrysler sales were off 7.7 percent in the final selling period, and were up 1.5 percent in the month compared with June a year ago.

"This is not unexpected, now that sales incentives are gone and inventories of imported cars are starting to be rebuilt," said Joseph Phillippi, an automotive industry analyst at E. F. Hutton in New York. "There's also a manufacturing recession in this country right now, so it's not surprising that sales were a little sloppy."

The seasonally adjusted annual rate of domestic sales was 7.3 million in the final selling period and 7.9 million for the month, compared with a normal 8 million.