Chinese stock brokerages are seeking to raise more than $6.2 billion from initial public offerings as capital constraints squeeze their operations.

Guotai Junan Securities Co, China's third-largest brokerage by revenue, is among six securities firms awaiting approval for an IPO, according to filings posted on the website of the China Securities Regulatory Commission.

They will be competing with about 600 companies seeking capital in a market where equities are trading near record-low valuations.