Countries defined as "within the region" will hold a 75 percent stake in the bank, the ministry said in a statement on its website, as delegates from 57 countries gathered in Beijing to witness the signing of the articles of agreement for the bank.
Fifty countries signed the agreement, the ministry said, as the remaining seven - Denmark, Kuwait, Malaysia, Philippines, Holland and South Africa and Thailand - had not yet won domestic approval.
India will have the second-largest share in the bank, followed by Russia, Germany and South Korea based on their capital subscriptions, according to the statement.
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The AIIB's authorized capital stock would be $100 billion, which would be divided into shares that have a value of $100,000.
The ministry added that the initial stakes and voting rights of China and other founding members would be gradually diluted as other members joined.
After getting approval from the majority of the board, the AIIB can increase its legal share capital and lower the share of countries within the region, but not lower than 70 percent, it said.