WASHINGTON — The economy nearly stalled in the first quarter with growth slowing to a pace of just 0.6 percent. That was the worst three-month showing in over four years.

The new reading on the gross domestic product, released by the Commerce Department Thursday, showed that economic growth in the January-to-April quarter was much weaker. Government statisticians slashed by more than half their first estimate of a 1.3 percent growth rate for the quarter.

The main culprits for the downgrade: the bloated trade deficit and businesses cutting investment in supplies of the goods they hold in inventories.

For nearly a year, the economy has been enduring a stretch of subpar economic growth due mostly to a sharp housing slump. That in turn has made some businesses act more cautiously in their spending and investing.

The economy's 0.6 percent growth rate in the opening quarter of this year marked a big loss of momentum from the 2.5 percent pace logged in the final quarter of last year.

Federal Reserve Chairman Ben Bernanke doesn't believe the economy will slide into recession this year, nor do Bush administration officials. But ex Fed chief Alan Greenspan has put the odds at one in three.

The first-quarter's performance was the weakest since the final quarter of 2002, when the economy recovering from a recession. At that time, GDP eked out a 0.2 percent growth rate. Economists were predicting the first-quarter performance this year would be downgraded, but not as much as it did. They were calling for a 0.8 percent growth rate pace.

GDP measures the value of all goods and services produced in the United States. It is considered the best measure of the country's economic fitness.

Many economists believe the first quarter will be the low point for this year. They expect growth will improve but still be sluggish.

The National Association for Business Economics predicts the economy will expand at a 2.3 percent pace in the April-to-June quarter.