China's Authorities Attempt to Prick Stock Bubble

``China's securities regulator jolted traders after the close of local bourses Friday when it banned a source of financing for margin trades and made it easier for short sellers to wager that stocks will fall. The Shanghai Composite Index fell 1.6 percent on Monday, following a tumble in offshore futures and exchange-traded funds linked to the world's second-largest stock market... The Shanghai Composite's 115 percent surge from last year's low on Jan. 20 is challenging authorities as they seek to weigh the benefits of rising share prices against the risk that individual investors will get burned by excessive speculation.''