Agricultural Bank of China has raised a record $22.1 billion in its initial public offering, a report said.

The bank has now claimed the title of the world's largest IPO after fully exercising the over-allotment option of its Shanghai share offering, Dow Jones Newswires said.

The lender raised an additional 9.11 billion yuan ($1.34 billion) from the Shanghai portion of the IPO by selling an extra 3.4 billion shares at 2.68 yuan each, the report said, citing a person familiar with the deal.

The previous record was set by Industrial and Commercial Bank of China, which raised $21.9 billion in its 2006 IPO.

AgBank - the last of China's Big Four state banks to list - raised a total of $19.23 billion from its shares before it started to trade in Shanghai and Hong Kong last month.

The bank said late last month in a statement to the Hong Kong Stock Exchange that it raised an additional $1.56 billion by selling extra shares in Hong Kong.
The over-allotment option, or so-called greenshoe, is a tool used by underwriters to limit a stock's volatility for a month after it lists.

It also allows a company to sell more shares than it originally planned if demand is strong.