This has been a year packed with history. We've watched the S&P 500 (^GSPC +0.19%), Nasdaq Composite (^IXIC +0.10%), and Dow Jones Industrial Average (^DJI +0.19%) eclipse 7,200, 25,000, and 50,000, respectively.
But this is just the beginning. Before the year ends, three of the largest private companies are expected to go public. Elon Musk's SpaceX has already confidentially filed its initial public offering (IPO) with regulators and is seeking a valuation of $1.75 trillion to $2 trillion. Meanwhile, artificial intelligence (AI) large language model (LLM) developers OpenAI and Anthropic are expected to go public later this year at valuations of close to $1 trillion each.
Mammoth gains for the Dow, S&P 500, and Nasdaq under President Trump may prove fleeting. Image source: Official White House Photo by Joyce N. Boghosian.
This combination of AI stocks heralding the charge, and America's largest public companies initiating record share buybacks, courtesy of President Donald Trump's Tax Cuts and Jobs Act, has propelled the Trump bull market to new heights. From a purely statistical standpoint, the Dow, S&P 500, and Nasdaq Composite have generated outsize returns under Trump.
However, the Trump bull market's staying power may be fleeting, with new rules pertaining to mega-IPOs representing the spark that could ignite a mammoth stock market correction.
Wall Street buzz surrounding SpaceX, OpenAI, and Anthropic is palpable
To give credit where credit is due, it's not hard to understand why investors are so excited about this trio of upcoming IPOs.
According to reports, SpaceX may allocate up to 30% of its shares for retail investors (significantly more than the 5% to 10% typically set aside for everyday investors), and is seeking to raise $75 billion. If accurate, Musk's company would more than double the largest IPO in history, Saudi Aramco, which raised $29.4 billion from its December 2019 debut.
The biggest IPO run in the history of the market
-- shirish (@shiri_shh) April 28, 2026
three $1T+ companies. possibly all going public in the next 12 months.
SpaceX IPO: $1.75T.
OpenAI IPO: $1T
Anthropic IPO: $1T
we're living through the greatest technological wealth creation in history. pic.twitter.com/44QuB3rpxi
SpaceX combines two of the hottest and largest addressable opportunities: space and artificial intelligence. The global space economy is projected to reach $1.8 trillion by 2035, per McKinsey & Company. Meanwhile, PwC analysts estimate AI can create up to $15.7 trillion in global economic value by 2030.
SpaceX was reportedly profitable on an EBITDA basis in 2025, per Reuters, and has since merged with AI start-up xAI, which also owns social media platform X (formerly known as Twitter).
There's an equal level of excitement for OpenAI, the brainchild of LLM ChatGPT, and Anthropic, the company behind Claude LLMs. Several of Wall Street's most influential companies have been steady investors and collaborators with these leading LLM developers.
As of this writing on May 1, 12 U.S.-listed stocks have reached the $1 trillion market cap plateau. By year's end, there may be 15, courtesy of the upcoming SpaceX IPO and the expectation that OpenAI and Anthropic will follow suit (likely in the fourth quarter).
Image source: Getty Images.
A new index inclusion rule for mega-IPOs can sink the Trump bull market
Unfortunately for investors, popularity and profitability aren't the same thing on Wall Street.
Effective May 1, 2026, the Nasdaq exchange implemented a new "Fast Entry" rule that allows large IPOs to bypass the typical waiting period (up to one year) before being included in the Nasdaq-100 index. To be eligible, a newly public company with a market capitalization within the top 40 of existing Nasdaq-100 components can be added after 15 trading days (roughly three weeks post-IPO).
For example, SpaceX, OpenAI, and Anthropic are all on track to be among the 15 largest public companies within the Nasdaq-100. This puts all three companies on the fast track to inclusion.
S&P Dow Jones Indices, which is responsible for adding and removing companies from the iconic Dow Jones Industrial Average and benchmark S&P 500, is also contemplating a rule change to accelerate admission to the S&P 500 for mega-IPOs. Specifically, the proposal would reduce the waiting period to six months from 12 and waive the profitability requirement (positive earnings in the most recent quarter and over the trailing four quarters).
Huge news. The S&P Dow Jones Indices has officially proposed big rule changes for "MegaCap" companies that could fast-track companies like @SpaceX into the S&P 500.
-- Sawyer Merritt (@SawyerMerritt) May 1, 2026
Proposed changes:
• Faster entry. Company would now only need to be public for 6 months (instead of 12 months)... pic.twitter.com/1HYJ1NCPF1
On the one hand, having the fast track to Nasdaq-100 and possible S&P 500 inclusion would be a tailwind for SpaceX, OpenAI, and Anthropic. Funds that track these market-cap-weighted indexes would be required to purchase shares in all three companies.
But there's another side to this story.
Historically, mega-IPOs have underperformed after their debuts. Since 1999, several brand-name companies have gone public, only to fall flat in the six months following their IPO.
Although Visa rallied 23% six months after its debut, Facebook (now Meta Platforms), Alibaba Group, General Motors, United Parcel Service, and Saudi Aramco fell by 38%, 9%, 8%, 11%, and 15%, respectively, over the same timeline.
History proves that investors have a terrible habit of being overzealous with IPOs, and this will almost certainly be the case once again with SpaceX, OpenAI, and Anthropic. The estimated price-to-sales ratios for all three companies are off the charts.
Fast-track/accelerated index inclusion for historically expensive and potentially unprofitable IPOs is a possible disaster in the making for the Trump bull market. The sizable weighting of these prospective IPOs in the Nasdaq-100 and/or S&P 500, coupled with the historical poor performance of mega-IPOs, portends trouble.
