BEIJING, May 7 (Xinhua) -- Shares fell for a second day on Wednesday, shedding 4.13 percent on profit-taking, led lower by securities firms and airlines.

    The benchmark Shanghai Composite Index closed at 3,579.15 points, down 154.36 points. The Shenzhen Component Index fell 723.37 points, or 5.28 percent, to 12,979.19 points. Losing shares outnumbered gainers by 761 to 88 in Shanghai and by 605 to 63 in Shenzhen

    Combined turnover shrank from 210.24 billion yuan (30.03 billion U.S. dollars) on Tuesday to 192.91 billion yuan on Wednesday.

    Qin Hong, an analyst with Bohai Investment, said the market had gone through a normal correction on Wednesday and the downtrend in Hong Kong had also dampened investor confidence.

    Hong Kong stocks slid 651.92 points, or 2.48 percent, to 25,610.21 on Wednesday.

    The benchmark Shanghai index opened lower at 3,716.45 and fell as low as 3,577.99 in the afternoon session amid heavy selling.

    None of the top 10 heavyweights managed to rise.

    PetroChina, the country's largest oil producer, dropped 2.23 percent to 17.94 yuan, while Sinopec, the largest oil refiner, plummeted 4.5 percent to 12.51 yuan.

    Financial shares were hurt by renewed concerns about further monetary tightening and banks fell across the board. Industrial and Commercial Bank of China, the country's biggest lender, slid 3.24 percent to 6.28 yuan. Bank of Communications tumbled 5 percent to 9.89 yuan.

    Brokerage shares, which gained on Tuesday, with many up by the daily 10-percent limit, were broadly lower. CITIC Securities, the country's largest securities firm, fell 7.45 percent to 37.78 yuan, with Changjiang Securities, another major brokerage, down 5.69 percent to 28.20 yuan.

    Airlines were affected by high world oil prices, which feed through to aviation fuel costs. Additionally, airlines shed recent gains that were driven by strong travel bookings over the May 1 national holiday.