The ride-hailing company, which could be valued at as much as US$120 billion in an IPO, is working with Bank of America Corp, Barclays Plc, Citigroup Inc and Allen & Co on preparations for the public listing, said the people, who asked not to be identified as the details aren’t public.

The banks join Morgan Stanley, which will lead the IPO for Uber, as well as Goldman Sachs Group Inc, the people said.

Uber’s public offering could be one of the five largest of all time in the US and is expected to be the biggest listing this year, netting millions of dollars in fees for the banks that work on the process.

The San Francisco-based startup confidentially filed paperwork for the IPO with regulators in Dec, but is yet to make the details of its plan public.

Representatives for Bank of America, Barclays and Citigroup declined to comment.

Allen & Co couldn’t immediately be reached outside of regular business hours. The bank mandates were first reported by Reuters.

Underwriters can make fees equal to about 3% to 5% of the gross proceeds on larger IPOs, though companies may negotiate lower fees on very large and high-profile listings.