SHANGHAI, China — China's biggest bank launched the world's largest initial public offering of stock yesterday, underscoring the nation's powerful economic growth and the significant strides made in its long-troubled financial sector.

Industrial & Commercial Bank of China, the largest of the country's big four state-owned banks, raised at least $19.1 billion in the first-ever dual debut on the Hong Kong and Shanghai stock exchanges.

Chinese officials are trying to prepare their top domestic banks to battle with global powerhouses like Citicorp and HSBC. Investors clamoring for Chinese bank stocks are betting on the country's rapid growth and that Beijing will do whatever it takes to make its showcase banks succeed, said James Barth, a banking expert at the Santa Monica, Calif.-based Milken Institute.

In Hong Kong, shares of the Beijing-based bank rose 14.6 percent from its initial offering price, on the high end of analysts' expectations. But in simultaneous trading in Shanghai, shares closed just 5.1 percent higher.

"It was disappointing to many investors and analysts," said Qiu Zhicheng of Haitong Securities in Shanghai. Chinese officials launched ICBC's stock at the same time in the two cities to give a boost to China's mainland stock markets, which have gained sharply this year after several years of poor performance.

But ICBC's weaker-than-expected launch on the 16-year-old Shanghai exchange shows how much further it has to go to catch up with established financial markets such as Hong Kong and build credibility with mainland Chinese investors.

"The trust issue is involved in a lot of this," said Andy Xie, former chief economist in Asia for Morgan Stanley in Hong Kong. "Most Chinese do not view the stock market as a place for long-term investment."

Nonetheless, stock analysts and economists regarded ICBC's debut as an overwhelming success. The offering attracted about $500 billion in orders, 25 times what was offered. Because of the extraordinary demand, the bank's stock sale was expected to rise to $21.9 billion — with $16 billion raised in Hong Kong and $5.9 billion in Shanghai.