SpaceX is working with at least 21 banks on its blockbuster initial public offering, people familiar with the matter said, one of the largest underwriting syndicates assembled in recent years.

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The listing, internally codenamed Project Apex, is expected to be among the most closely watched stock market debuts on Wall Street.

The public offering, expected in June, is estimated to value the rocket company controlled by founder and CEO Elon Musk at $1.75 trillion.

Morgan Stanley, Goldman Sachs, JPMorgan Chase, Bank of America and Citigroup are serving as active bookrunners, or the lead banks managing the deal, the people said, asking not to be identified because the process is not public. A further 16 banks have signed on in smaller roles, they added.

About half of the banks' names have not previously been reported.

The size of the syndicate underscores the scale and complexity of the planned offering.

Banks in addition to the bookrunners include:

• Allen & Co
• Barclays
• Brazil's BTG Pactual
• Deutsche Bank
• The Netherlands' ING Groep
• Macquarie
• Mizuho
• Needham & Co
• Raymond James
• Royal Bank of Canada
• Societe Generale
• Banco Santander
• Stifel
• UBS
• Wells Fargo
• William Blair

The banks are expected to take on roles in institutional, high-net-worth and retail investor channels as well as in different geographic regions, Reuters previously reported.

The plan is subject to change and additional banks could still be added, the sources said. Texas-based SpaceX did not immediately respond to a request for comment.

Bank of America, Barclays, Deutsche Bank, Goldman Sachs, JPMorgan, Mizuho, Santander and Wells Fargo declined to comment. The other banks did not immediately respond to requests for comment.

Large IPO syndicates have become more common for mega deals in recent years. Chip designer ARM Holdings worked with close to 30 banks on its 2023 listing, while Alibaba Group assembled a similarly large group of underwriters for its record-breaking 2014 debut.