Hong Kong, China – One of China's big banks has debuted on the Shanghai stock market.

Agricultural Bank of China, or AgBank for short, has raised over $19 billion. If enough investors show interest in the stock, the listing could bring in another $3 billion and become the largest initial public offering in the world.

With so much buzz, it looked as though the listing was headed for a strong first day. But that never happened.

Many investors are worried about the state of the global economy, including China's slowing growth.

Analysts such as Victor Shih with Northwestern University believe the country's banks have made bad bets funding projects by some "reckless" state-owned companies.

Shih estimates the Chinese financial system is clogged with up to $440 billion of defunct loans. In AgBank's case, some investors are concerned the bank's government mandate to lend to farmers could limit its loan portfolio.

One financial analyst pointed out to me that many of China's big banks (AgBank, Bank of China, ICBC) are rushing to raise funds - perhaps billions of dollars - to help replenish their reserves after a record year of government directed lending.

AgBank has a customer base of around 320 million people - bigger than the entire population of the United States. At the listing ceremony in Shanghai, the bank's chairman said by purchasing AgBank shares, investors are "buying into the future of China's economy."

Given all the uncertainty, is now the right time?