Anthropic Plans to List on Nov. 19: Historical Data Shows Buying on First Day Is Not a Good Decision, With Average 60-Trading-Day Return of -6%

A comparison of seven mega-IPOs, including SpaceX, shows that when buying at the first-day closing price and holding for 60 trading days, only three companies gained and just two outperformed the S&P 500 over the same period. The size of an IPO and the attention it garners do not universally translate into post-listing excess returns.

This analysis covers six companies that listed in the U.S. between 2008 and 2025 with IPO proceeds of at least $8 billion, along with SpaceX, which listed in 2026, as a recent case study. Proceeds exclude over-allotments, and these seven companies do not represent all mega-IPOs through 2026.

Note: The backtest uniformly assumes buying at the closing price on the first day of trading, with holding periods of 20 and 60 trading days, respectively; the S&P 500 uses the exact same start and end dates as each stock.

Over a 20-trading-day holding period, the seven stocks fell by an average of 0.64%, with three outperforming the broader market; extending the period to 60 trading days, the average return dropped to -5.92%, the proportion outperforming the broader market fell to 28.6%, and the stocks lagged the S&P 500 by an average of approximately 9.12 percentage points.

Among them, although General Motors rose 5.62%, it still underperformed the broader market over the same period; Rivian shifted from a 14.56% gain over 20 trading days to a 42.06% decline over 60 trading days. SpaceX fell in both observation periods and also failed to outperform the S&P 500.

These disparities indicate that early post-listing gains may quickly be replaced by earnings expectations and valuation adjustments. These samples demonstrate that the higher the first-day purchase price, the larger the valuation premium that subsequent growth needs to absorb.

The primary basis for Anthropic's appeal to investors is the rapid commercial scaling of Claude. Third-quarter revenue reached approximately $17 billion, exceeding the total for the first half of the year; as of October 31, its annualized revenue run rate reached $81 billion, an increase of $10 billion from the end of September.

According to Bloomberg, the offering is seeking a fully diluted valuation of approximately $1.4 trillion. Calculated at an annualized revenue run rate of $81 billion, this corresponds to roughly 17.3 times; based on a simple annualization of actual third-quarter revenue, it is approximately 20.6 times. The appeal of the valuation is therefore highly dependent on whether recent growth can be sustained.

Claude's expansion from coding to spreadsheets, meetings, and other workplace scenarios is expected to increase paying users and call volumes. However, how much return revenue growth can generate for shareholders still depends on the cost of serving these customers.

The prospectus shows that third-quarter compute and infrastructure expenses were approximately $9.9 billion, with their share of revenue rising from 48% in the second quarter to 58%; the adjusted operating margin fell from 19% to 15% over the same period. While new demand expanded revenue, it also brought higher compute expenditures.

For investors buying after the listing, the offering valuation is merely a reference point. If the stock price rises significantly on its first day of trading without a concurrent increase in revenue and earnings expectations, the valuation actually paid will be even higher. Anthropic needs to absorb this premium through growth in enterprise paying customers, improvements in unit compute costs, and profit margin expansion to translate business growth into shareholder returns.

This content was translated using AI and reviewed for clarity. It is for informational purposes only.