Guosen Securities Co, the top- ranked arranger of initial public offerings in China, has more than doubled the workforce at its Hong Kong unit this year as Chinese investment banks challenge Goldman Sachs Group Inc and Morgan Stanley outside their home market, Bloomber reported Monday.

Guosen Securities (HK) Financial Holdings Co has about 200 employees, up from less than 100 at the end of last year, Chief Executive Officer Lu Xiao Ning said in a July 20 interview. The firm plans to add 500 square meters of office space to the 1,500 square meters occupies at One Exchange Square and Li Po Chun Chambers in central Hong Kong, he said.

The expansion comes as competition for arranging share sales squeezes fees in Hong Kong, while rivals including UBS AG have said rising banker compensation is eroding margins. Average fees for IPO underwriting in Hong Kong this year fell to 2.2 percent of the funds raised from 3.5 percent in 2001, according to data compiled by Bloomberg.

Guosen Securities, based in Shenzhen and controlled by the city's government, has worked on 18.7 billion yuan ($2.9 billion) of IPOs in China so far in 2011, more than any other bank, Bloomberg data show. Fees for those deals averaged 4.6 percent of funds raised, according to the data. The Hong Kong unit, which got a license to underwrite share sales in April, hasn't managed any equity offerings in the city so far.