Most listed companies in China are reporting weaker first-quarter results, demonstrating that economic growth is losing momentum.

By Sunday, 713 listed companies had released their first-quarter results, with 328 reporting lower profits and 118 registering losses.

This week, another 1,677 companies are set to give first-quarter results, with 299 having earlier estimated losses or lower profits.

All of the companies listed in Shanghai and Shenzhen must report first-quarter results by May.

GDP data released earlier this month by the National Bureau of Statistics showed the economy grew 8.1 percent in the first three months of 2012. That was the slowest pace in nearly three years but still slightly above the full-year 7.5 percent target set by Premier Wen Jiabao in March.

The NBS has reported other statistics recently that came in at the lower range of expectations: March industrial output rose 11.9 percent, retail sales expanded 15.2 percent and first-quarter fixed-asset investment, a principal driver of China's economy, grew 20.9 percent.

Big manufacturers have led the decline in earnings reports, hit by slowed fixed-asset investment growth. Shantui Construction Machinery Co Ltd, a heavy machinery maker, said it expects its first-quarter profit to drop 50 to 100 percent.

The steel producer Beijing Shougang Co Ltd has estimated a loss of 140 million yuan ($22.2 million) to 160 million yuan, compared with a year-earlier profit of 32 million yuan. The steel industry association has said the industry lost about 1 billion yuan in the first quarter, its first quarterly loss since 2000.

The "busy season being not busy" helped depress corporate income in the first quarter", said Zhang Bo, an analyst at UBS AG.

However, he said he believes things are about to bottom out. GDP and consumer price index growth will top decreasing in the third quarter and help corporate incomes rebound.

Qu Hongbin, a China economist with HSBC Holdings Plc, said GDP growth will bounce back to 8.5 percent in the third quarter, after the government lowers the reserve requirement ratio, boosts spending and cuts taxes. For the full year, he expects growth to average 8.6 percent.

Public companies' profit will rise 10 percent year-on-year in the third quarter and 37 percent in the fourth, partly helped by a low base of comparison, Zhang said. For the whole year, profits will rise 5.4 percent, on an income increase of 17 percent.

However, the real estate sector, one of the nation's pillars, is more worrying. Investment growth in the sector plummeted to 19.5 percent year-on-year in March from 27.8 percent in the first two months. The figure isn't likely to see a significant uptick, because property curbs will persist.