The 10 firms buying into the state-owned Postal Savings Bank of China (PSBC) include Internet giants Alibaba and Tencent, UBS Group bank, and Singapore's Temasek Holdings, the official news agency Xinhua said.
The institution, founded in 2007 in an effort to boost financial services in rural areas of China, has 40,000 branches -- more than any other bank in the country -- and has served nearly half a billion customers as of September, according to its website.
Beijing says it is pushing reforms among its lumbering state-owned enterprises (SOEs) as it seeks to make the economy more efficient, with measures including initial public offerings to try to instill them with more market discipline.
PSBC is expected to list in Hong Kong in 2016, according to reports.
Xinhua quoted the bank's president Lu Jiajin as saying the sale of nearly 17 percent of the equity was "a win-win cooperation for both PSBC and its strategic investors. It is also a typical example for the world and China to win in mutual benefits".