Discussions around mega-cap IPOs began to pick up in 2025 as market attention increasingly shifted toward companies such as SpaceX, Anthropic, and OpenAI, and the question of whether, and how they might eventually access public markets. These potential IPOs have attracted significant market attention, driven by substantial revenue bases despite not yet being profitable. Importantly, they would also give public-market investors access to business models that are largely unavailable today, most notably conversational AI and large language models that many of us already use, as well as exposure to the commercial space industry through SpaceX.

Investors are also closely focused on the underlying assets and platforms embedded within these businesses. SpaceX controls Starlink, an already well-established satellite internet provider, alongside its broader space exploration and Starship programs. OpenAI owns and operates ChatGPT, while Anthropic develops and operates Claude and Claude Code.

However, with revenues already measured in the multiple billions, high growth expectations tied to their AI business models, and several rounds of private financing behind them, these fan-favorite IPOs are expected to come to market at valuations that exceed those of many established public companies in major indices.

Key Definitions:

• Market Capitalization: A company’s total value. For public companies, this is calculated by multiplying the share price by the total number of outstanding shares.
• Free-Float Market Capitalization: The value of a company based only on the shares available for public trading, excluding those held by insiders, founders, and strategic owners.
• Fast-Tracking: Index rules that allow a very large IPO to be added to a benchmark within days of listing, rather than waiting for standard inclusion criteria and review periods to be me.t
• Dual-class Shares: A structure issuing share types with unequal voting rights, letting founders and insiders keep control while owning a minority stake.
• Lock-Up Period: The period following an IPO during which insiders are unable to sell their shares; its expiry typically results in additional shares being released into the public market.

S&P implemented a clear two-tier approach to mega-cap IPO inclusion following its June 2026 consultation. The S&P 500 remains unchanged, with all existing requirements, such as a 12 month seasoning period, minimum float, and sustained profitability, still fully enforced, resulting in a delayed and more stringent path for newly listed companies. In contrast, S&P introduced a fast-track mechanism specifically for its broader indices, such as the Total Market Index and Completion Index, allowing large IPOs that meet defined float-adjusted market cap thresholds to be added shortly after listing, based on first-day pricing and with advance notice. Importantly, this pathway removes profitability and seasoning requirements, enabling faster inclusion in the broader market. Overall, the outcome creates a clear distinction: accelerated access to broad market exposure, but a slower, criteria-driven route into the flagship S&P 500.

MSCI does not need to change its rules to deal with large IPOs. Instead, it relies on its existing fast-track process, which already allows very large companies to be included relatively quickly after listing. Inclusion is mainly driven by size, liquidity, and free float, with no profitability requirement and no fixed seasoning period, making MSCI’s approach more flexible than that of indices such as the S&P 500.

A key difference is how MSCI treats free float. Rather than applying a hard minimum threshold, MSCI looks at float in absolute terms and adjusts for company size. As a result, very large companies with relatively low initial float can still qualify, as long as the overall market capitalization and available float are large enough.

In practice, this means that large, liquid IPOs can be added to MSCI benchmarks relatively soon after listing, even when public ownership is limited at launch.

The Nasdaq-100 includes companies that meet several core eligibility criteria, including a primary listing on the Nasdaq Global Select or Global Market, exclusion from the financial sector, a minimum three-month average daily traded value of $5 million, and a ranking among the 100 largest non-financial Nasdaq-listed companies by market capitalization (with fast-track candidates typically requiring an estimated market cap of around $102 billion). Unlike the S&P 500, there is no profitability requirement, and the index uses a modified market-cap weighting methodology while excluding REITs, SPACs, and when-issued securities. Recent rule changes implemented on May 1, 2026, further accelerated inclusion for mega-cap IPOs, allowing entry as early as 15 trading days post-listing, removing the minimum float requirement, applying a size-adjusted float multiplier for low-float names, and introducing new quarterly ranking tests.

Solactive’s latest consultation period, which closed May 1, 2026, introduces a structured fast-track framework for mega-cap IPOs, enabling newly listed companies that meet predefined size, liquidity, and eligibility thresholds to be added to indices outside of the standard rebalancing schedule. The approach is designed to ensure more timely inclusion of large, market-relevant IPOs, while maintaining a rules-based process through an IPO review mechanism that limits discretion. In addition, the changes formalize clearer eligibility criteria and implementation timelines across Solactive’s core benchmark families, improving consistency and transparency in how IPOs are treated. Overall, the update reduces the historical lag to inclusion, enhances index responsiveness to significant new listings, and aligns Solactive’s methodology more closely with evolving industry standards and investor expectations.