Hong Kong shares tumble 3.4 pct to 15-week low

(Updates to midday)

HONG KONG, July 8 (Reuters) - Hong Kong shares slid 3.4 percent to a 15-week low on Tuesday, with all the Hang Seng Index .HSI stocks in the red, as investors dumped blue chips in the absence of any market-boosting measures from China.

Bourse operator Hong Kong Exchanges & Clearing Ltd (HKEx) (0388.HK: Quote, Profile, Research) tumbled 5.6 percent to its lowest level since mid-August 2007, as analysts slashed their target price on the stock on dwindling turnover. [ID:nHKF079283]

Index heavyweights joined in the slide, with China Mobile (0941.HK: Quote, Profile, Research) falling 3 percent and HSBC Holdings (0005.HK: Quote, Profile, Research) dropping 2.1 percent.

"Yesterday's rally was not really supported by any favourable announcements from the Chinese government, so investor confidence is still languishing," said Steven Leung, director with UOB Kay Hain.

"The market is still struggling to find a bottom, despite being heavily oversold."

The benchmark Hang Seng Index .HSI gained 2.3 percent on Monday, rising the most in 13 weeks, as Chinese banks and property stocks rallied amid talk of policy-boosting measures.

The benchmark Hang Seng Index .HSI ended Tuesday morning down 747.65 points at 21,165.41, a 15-week low.

Mainboard turnover rose to HK$35.88 billion ($4.6 billion) from HK$30 billion at midday on Monday.