(Adds lagging, coincident indexes)
WASHINGTON, April 20 (Reuters) - A key gauge of future economic activity fell for the third month in a row in March, showing the recession may persist through the summer, a nonprofit research group said on Monday.
The Conference Board's Leading Economic Index declined 0.3 percent last month, steeper than the 0.2 percent analysts polled by Reuters were expecting. It also fell 0.2 percent in February, which was originally reported as a 0.4 percent drop.
"The recession may continue through the summer, but the intensity will ease," said Ken Goldstein, an economist at the Conference Board, in a statement.
The index has not risen in the last nine months. In September and December it was unchanged and it experienced the largest drop during that period in October, when it fell 1 percent.
Real money supply and the yield spread both showed strength in March, but not enough to counterbalance the drag of building permits, stock prices and supplier deliveries.
Over the last six months, the index has fallen 2.5 percent, compared to the smaller 1.4 percent drop for the previous six months.
The Coincident Index, a measure of current conditions, fell for the third month in a row, by 0.4 percent, primarily due to declines in employment and industrial production.
The Lagging Index, which provides a glimpse backward, has been on a downward trend since July 2007, the Conference Board said. Its 0.4 percent decline in March was caused by weakness across all of its components, which include duration of unemployment, inventory levels, and outstanding loans.
"There have been some intermittent signs of improvement in the economy in April, but the leading economic index and most of its components are still pointing down," Goldstein said. (Reporting by Lisa Lambert; Editing by Neil Stempleman)