A public listing at a potential valuation of more than $US1.75 trillion ($A2.52 trillion) would signal that space exploration has moved from a speculative venture to a mainstream investment theme.
SpaceX's growth has been driven by its reusable rockets and the Starlink satellite internet network.
The filing comes after SpaceX merged with Musk's artificial intelligence startup xAI in a deal that valued the rocket company at $US1 trillion and the developer of the Grok chatbot at $US250 billion.
SpaceX is hosting an analyst day on April 21, encouraging research analysts to attend in person, according to a person familiar with the matter who requested anonymity to discuss confidential information.
The company is also offering analysts an optional visit to xAI's "Macrohard" data centre site in Memphis, Tennessee, on April 23, and plans to hold a virtual session on May 4 to discuss financial models with banks, where banking teams are invited to participate, the source said.
Musk, the world's richest person, runs a sprawling business empire that spans electric vehicles, space and satellite ventures, AI and social media.
"Investors could use a sum-of-the-parts analysis but, like with Tesla, SpaceX's valuation could very much fluctuate wildly based off how much the public believes in Musk's vision," said Angelo Bochanis, data and index associate at Renaissance Capital, a provider of IPO-focused research and ETFs.
"So far, investors seem to be clamouring for any sort of exposure to SpaceX."
SpaceX did not immediately respond to a Reuters request for comment.
The Starbase, Texas-headquartered firm could seek to raise more than $US50 billion in the IPO, handily surpassing the 2019 flotation of Saudi Aramco, which remains the largest IPO on record.
A blockbuster SpaceX debut could jolt the IPO market back to life after years of subdued activity, with market participants expecting strong demand from both retail and institutional investors, some drawn by Musk's brand and others seeking exposure to SpaceX's fast-growing space and satellite businesses.
SpaceX is the world's most valuable privately held company, based on the valuation implied by its merger deal with xAI.
The rocket startup was last valued at about $US800 billion in a secondary share sale independently.
Several other high-profile startups, including ChatGPT maker OpenAI and rival Anthropic, are also said to be weighing large IPOs, setting up a broader test of investor appetite for new listings.
Many large startups have remained private for longer, tapping deep pools of capital in private markets, but a listing by a company such as SpaceX could encourage more of them to pursue public offerings.
Bloomberg News first reported on the confidential filing earlier on Wednesday.
A confidential filing allows a company to submit IPO documents to regulators privately, giving it time to address feedback and refine disclosures away from public scrutiny.
