Refinitiv, the financial data firm co-owned by the Blackstone Group LP and Thomson Reuters Corp., has confidentially filed for an initial public offering of its Tradeweb Markets LLC business.

The bond-trading platform could be worth more than $4 billion in an IPO, said the people, who asked to not be identified because the matter isn’t public. One of the people said the timing of the potential IPO could be delayed by the U.S. government shutdown, which could broadly depress pending stock sales and mergers

Blackstone acquired 55 percent of Refinitiv — as Thomson Reuters’s financial and risk unit was renamed — for $17 billion last year with co-investors Canada Pension Plan Investment Board and GIC, Singapore’s sovereign wealth fund.

Tradeweb, based in New York, builds and operates over-the-counter marketplaces for fixed income and derivatives products. Formed in 1998, several large banks including Deutsche Bank AG, UBS Group AG and Royal Bank of Scotland Group Plc are among its investors.

Refinitiv Chief Executive Officer David Craig said in an interview with trade publication Financial News in October that the company was considering an IPO for Tradeweb.

Bloomberg LP, the parent company of Bloomberg News, competes with Thomson Reuters and Refinitiv in providing news, data and information to the financial industry.