By Laura He, MarketWatch

HONG KONG (MarketWatch) -- Hong Kong stocks swung between gains and losses before closing flat on Monday, after two separate gauges of China's manufacturing activity both showed a slight slowing last month.

The HSBC China Manufacturing Purchasing Managers' Index dropped to 50.2 in August from 51.7 in July, HSBC said on Monday. Earlier, the official manufacturing PMI for last month also fell to 51.1 from 51.7 in July, according to official data

In Hong Kong, the benchmark Hang Seng Index ended up less than 0.1%.

Mainland Chinese banks traded mixed, with both Bank of China Ltd. and Agricultural Bank of China Ltd. down 0.3% in Hong Kong. China Construction Bank Corp. lost 0.9%, after its interim results showed a 9% rise in profit but also an increase in nonperforming loans during the first half of the year. However, China Merchants Bank Co. ended up 0.3%, after it posted a 16% jump in first-half net profit.

Several tech stocks were poorly bid, with software developer Kingdee International Software Group Co. declining 2.4%, game developer NetDragon Websoft Inc. off 2%, and software developer Kingsoft Corp. lower by 1.8%.

Other market movers included Macau casino operator Sands China Ltd. , down 3.2%, local rival Galaxy Entertainment Group Ltd., off 2.9%, while electric-car maker BYD Co. Ltd. improved by 1.5%, and auto maker Dongfeng Motor Group Co., Ltd. tacked on 1.4%.

In other Asian markets, Japan's Nikkei Average rose 0.3%, the broader Topix index added 0.4%, while the yen (USDJPY) was softer against the dollar, trading at Yen104.17 from Yen104.04 a day earlier.

Elsewhere, the Shanghai Composite Index finished 0.8% higher, Sydney's S&P/ASX 200 ticked up 0.1%, while Seoul's Kospi Composite Index closed flat.

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