China's efforts to stimulate its economy are turning the nation's biggest brokerage into a bond-market powerhouse.

CITIC Securities Co overtook HSBC Holdings Plc in 2015 as top arranger for emerging-market debt securities worldwide as rate cuts by the People's Bank of China, the central bank, reduced borrowing costs and boosted yuan-denominated bond issuance in the onshore market, data compiled by Bloomberg show.

CITIC last year managed the equivalent of almost $53 billion worth of offerings with maturities of 18 months or more, almost all of that yuan-denominated, or 4.3 percent of the global market. HSBC, which dominated the developing-world bond market from 2008 to 2014, managed $46.2 billion worth for a second-place market share of 4 percent.

Premier Li Keqiang has encouraged expansion of China's bond market to help wean firms from reliance on loans from shadow banks. Central bank rate cuts also helped government and corporate issuance onshore surge 66 percent last year to 9.9 trillion yuan ($1.5 trillion), according to debt clearinghouse Chinabond.

Brokerages are also winning business overseas. CITIC's underwriting in foreign currencies rose to 11.6 percent of all its developing-world debt business in 2015 from 2.8 percent the previous year.