The U.S. economy lost momentum in the second quarter of the year, according to figures released Friday, which may raise concerns of an extended soft patch if not an outright contraction.

Real gross domestic product -- the inflation-adjusted, seasonally adjusted value of all goods and services produced in the United States -- rose at a 2.4% annualized rate in the second quarter, well below the average 4.4% increase over the last six months.

The 2.4% increase in GDP was close to the 2.5% expansion expected by economists surveyed by MarketWatch. However, the rate of expansion in the first quarter was revised up to a 3.7% rise compared with the prior estimate of a 2.7% increase.

Economists believe that the growth was fairly strong in April and May but hit a rough patch in June. So the economy is going into the second half of the year with little momentum.

"The post-recession rebound is history," said Bart van Ark, chief economist at the Conference Board.

"We don't foresee a double dip," he continued, "but we do expect growth to slow even more markedly" -- to what he pegged as a 1.6% annualized rate for the second half of the year.

Investors reacted negatively to the report, with losses deepening in futures on the Dow Jones Industrial Average after the data were released.

Bond investors, confident the coast remains clear as far as inflation goes, bought U.S. Treasurys as two-year note yields sank to record lows.

Annual revisions released at the same time as the first estimate for second-quarter GDP show that the Great Recession was deeper than previously thought.

During the recession, real GDP decreased at a 2.8% average rate, down from the prior estimate of a 2.5% rate.

At the same time, the recovery, already one of the slowest, has been a bit slower. From the third quarter of 2009 to the first quarter, the economy grew at a 3.4% annual average rate, just below previous estimate of a 3.5% increase.

Although the increase in GDP in the quarter was not as strong as the first quarter, many of the details of the report were positive. Much of the deceleration was due to the trade sector. Consumer spending was only slightly weaker than the first quarter.

Now that the revisions have been released, the National Bureau of Economic Research may move to make a formal call on the end of the recession. Most economists think the recession ended in June 2009.

Final sales, which exclude inventories, rose at a 1.3% rate in the second quarter after rising 1.1% in the first quarter. Consumer spending slowed to a rise of 1.6% after rising at a 1.9% annual pace in the previous two quarters.

Consumer spending added 1.2 percentage points to GDP.

Spending on durable goods rose 7.5%, spending on nondurable goods rose 1.6%, and spending on services increased 0.8%.

The savings rate rose to 6.2%, the most since 1998. Real disposable income rose 4.4%.

Business investments rose at a 17% annual rate in the second quarter after a 7.8% gain in the first quarter. Investments in structures rose 5.2%, and investments in equipment and software rose at a 21.9% pace. Business fixed investment added 1.5 percentage points to growth.

Inventories increased by $75.7 billion U.S. The change in inventories added 1.1 percentage points to growth.

Investments in housing increased at a 27.9% annual rate after falling for the last two quarters. Residential investments added six tenths of one percentage points to growth.

Imports grew at a much faster pace the exports during the second quarter. Exports rose at a 10.3% rate. Imports soared at a 28.2% clip, the most in 34 years, as U.S. consumers and businesses stopped buying. Net exports subtracted 2.8 percentage points from growth as the trade gap widened. Imports had a record negative contribution to quarterly GDP.

Final sales to domestic purchasers -- a measure of domestic demand -- rose 4.2% after rising 3.5% in the first quarter.

Government spending rose at a 4.4% annual pace after a 1.6% drop in the first quarter. Spending by state and local governments rose 1.3%. Federal spending rose 9.2%. Government spending added nine-10ths of a percentage point to growth.

The price index for domestic purchases (prices paid by U.S. residents) rose 0.1% in the quarter. Consumer prices also rose 0.1%, while core consumer prices (which exclude food and energy) rose 1.1%.

In current dollar terms, GDP rose 4.1% to at annual rate of $1.23 trillion U.S.