Anthropic's $2 Trillion Valuation Test Hits S&P 500

Anthropic's initial public offering (IPO) is set to test the market demand for exposure to artificial intelligence (AI). The company plans to go public before the end of October, with a valuation target of $2 trillion or more. This would make it one of the largest IPOs in history, surpassing Space Exploration Technologies.

The S&P 500 index funds will not immediately buy into Anthropic's stock due to the rules governing mega-cap listings. By definition, these funds must buy whatever is added to the list of stocks, but they cannot do so for at least 12 months. This means that Anthropic won't be included in the S&P 500 until late 2027.

Despite this, two of the index's largest companies already own Anthropic, providing some exposure to holders of the index funds. Amazon reported $16.8 billion of pretax gains on its Anthropic position in the first quarter of 2026. Alphabet also has a stake in Anthropic.