The filing sets up what could be the largest technology IPO on record, with public market pricing expected to test whether frontier AI companies can sustain private-round valuations once audited financials are visible to all investors. The simultaneous path to market for both OpenAI and Anthropic creates an unprecedented side-by-side comparison of rival AI economics, which will either validate or reprice assumptions embedded across the entire private AI funding ecosystem. Revenue multiples for enterprise AI contracts and private-round benchmarks across the sector face a hard reset once the public S-1 lands. Microsoft's roughly 27% stake and the DOJ's active interest in AI infrastructure concentration are live variables that could complicate the review timeline.-OpenAI filed a confidential S-1 with the SEC on May 22, tentative September 2026 IPO is the chatter, led by Goldman Sachs and Morgan Stanley at a valuation of up to $1 trillion.Summary:OpenAI submitted a confidential draft S-1 to the SEC on May 22, formally initiating its IPO processGoldman Sachs, Morgan Stanley and JPMorgan are leading the offering; CEO Sam Altman is said to be targeting a September 2026 listingThe company's last private valuation was set at $852 billion in a $122 billion funding round in March 2026, the largest private fundraise on record; analysts project a public valuation above $1 trillionAltman noted the filing does not mean the company is ready to go public, and flagged that some things may be easier to complete while still privateOpenAI acknowledged the filing would leak and chose to announce it proactivelyRival Anthropic is targeting an October 2026 IPO at a valuation above $900 billion, setting up a near-simultaneous dual listing of the two leading frontier AI companiesOpenAI has filed a confidential draft registration statement with the US Securities and Exchange Commission, formally launching the process toward a public offering that could value the ChatGPT maker above $1 trillion and rank among the largest technology IPOs in history.The company submitted its S-1 on May 22, with Goldman Sachs, Morgan Stanley and JPMorgan leading the deal. CEO Sam Altman is apparently targeting a September 2026 debut, though he was careful to note that initiating the filing process is not the same as being ready to list, adding that certain strategic moves may be more easily completed while OpenAI remains private.OpenAI's most recent private valuation of $852 billion was set in March, when the company closed a $122 billion funding round, the largest in private market history. Public market analysts expect the offering could price above $1 trillion, which would exceed every technology IPO on record.The company chose to announce the confidential submission proactively, with Altman acknowledging he expected it to leak regardless.The filing will eventually force full disclosure of OpenAI's revenue and cost structure. The company is generating roughly $25 billion in annualised revenue but is reported to lose more than a dollar for every dollar it earns. Rival Anthropic is pursuing its own public listing, targeting October 2026 at a valuation above $900 billion. The near-simultaneous debut of both companies will give investors the first direct, audited comparison of frontier AI economics at scale. This article was written by Eamonn Sheridan at investinglive.com.