How Megacap IPOs in 2026 Could Reshape Global Benchmarks

After a subdued 2025, the IPO market is poised for a potential surge in 2026.¹ A backlog of large, venture-backed companies that are disproportionately concentrated in high-growth segments stands ready to go public.² Given their size (ranging from USD 50 billion to USD 1 trillion), these firms could reshape global equity benchmarks, redefine sector leadership and redirect capital flows through index-tracking strategies.

Since MSCI equity indexes are built on free-float-adjusted market capitalization, each IPO simultaneously expands the investable universe and shifts index weights as private ownership converts to public float. To understand this, we modeled the addition of the 10 largest companies in the MSCI All Country Venture-Backed Private Company Index to the MSCI ACWI Investable Market Index (IMI) as a proxy for such a megacap IPO scenario. Financial media widely cite several of these firms as IPO candidates, and they collectively represent some of the economy’s highest-growth areas, including AI software platforms, fintech and new-economy industrials such as aerospace and defense.

Top 10 constituents of the MSCI All Country Venture-Backed Private Company Index as of Jan. 30, 2026. Estimated valuations are obtained from MSCI data partners and modeled using venture-capital funding rounds, secondary-market trades, price events and public comparables. Classifications of private companies using MSCI PACS^TM, a global standardized taxonomy for private assets.  

Because free float at IPO is uncertain, we tested a range of plausible free-float outcomes (5%, 10%, 25% and 95%) and assessed index inclusion.³ The 95% case is not meant to represent an immediate post-IPO float. Rather, it approximates a terminal state in line with the average free float of the four U.S. sectors represented by these companies.

The private valuations are large enough that, at higher float levels (25% or more), all 10 firms would qualify as index constituents. At lower float levels, however, not all companies would qualify since free-float-adjusted market cap determines inclusion.⁴ In the 95% terminal-state scenario, three IPOs ranked among the top 30 constituents of the MSCI ACWI IMI by index weight.  

Data as of Jan. 30, 2026. Each vertical line in the right chart spans the highest and lowest rank of the included IPOs by index weight in the MSCI ACWI IMI for that float scenario. As of Jan. 30, 2026, the MSCI ACWI IMI had 8,206 constituents. 

We assumed that every company is U.S.-listed, which would give global benchmarks incremental U.S. weight. For asset owners and wealth managers that treat the MSCI ACWI IMI as a global reference, this drift can translate into marked reallocations and potential discomfort around increased U.S. concentration, as the offsetting changes are spread across other countries.⁵ At 25% float scenario, the U.S. weight in MSCI ACWI IMI rose from 61.75% to 62.03%, and in the 95% terminal-float scenario it rose to 62.78%. In the simulation’s largest inclusion outcomes, the largest declines occurred in Japan (-0.15%), the U.K. (-0.09%) and Canada (-0.08%). While the percentage changes look modest on paper, benchmark weights can scale into significant dollar flows quickly when implemented by investors replicating the index.

If the global story is “more U.S.,” the domestic story is “different U.S.” The hypothetical IPO cohort leans heavily into application software and also adds a meaningful aerospace and defense component, while introducing incremental weight in interactive media and services and payment processing.

Within the MSCI USA IMI, the footprint of the industrial and information technology sectors increased the most. The most notable shift, however, is within tech itself — from the infrastructure layer (semiconductors and hardware) to the platform and application layer (software and AI adopters) — purely through the entry of new constituents.

Changes based on the 25% float scenario. Data as of Jan. 30, 2026, using the MSCI USA IMI. Color coding of subindustries is set to match the sectors to which they belong. 

At the constituent level, the largest MSCI USA IMI companies face the steepest weight declines as IPOs claim market share. If it became public, Space Exploration Technologies Corp. could become the fourth-largest industrials constituent.

Data as of Jan. 30, 2026. Only those sectors where IPOs were added are shown. Within sectors, weights were renormalized to 100%.  

Where investors would be most directly affected, however, is index turnover, which can introduce trading events and increase implicit costs. In the 25% float scenario, MSCI USA turnover is 1.28% and MSCI USA IMI turnover is 1.16%.⁶ Turnover was higher within sectors. Industrials accounted for a large share (3.34% for USA IMI industrials), with communication services (1.86%) and information technology (1.7%) following. 

Based on the assumptions, a USD 100 million MSCI USA IMI allocation would require USD 1.16 million in total rebalancing: USD 1.16 million in IPO purchases and USD 1.16 million in sales of existing holdings (proportional to market cap). Net sector flows could be +USD 202,000 for industrials, +USD 118,000 for information technology, and (-) USD 109,000 for consumer discretionary.

IPOs could impact billions in global flows

At scale, these portfolio adjustments can translate to substantial market flows. With trillions globally tracking relevant MSCI indexes through ETFs and index funds, below we show estimated aggregate inflows to the 10 IPOs (given a 25% float scenario) and the largest outflows from down-weighted holdings.

Flow estimates based on MSCI Index AUM dataset (with AUM in ETF index products as of Jan. 30, 2026 and AUM in non-ETF index products as of Sept. 30, 2025), covering USD 5.79 trillion. Analysis filtered for (1) indexes with ≥ USD 5 billion AUM (USD 5.17 trillion coverage), (2) market-cap weighted or capped methodologies, and (3) U.S. regional exposure, resulting in 20 indexes with USD 1.86 trillion in tracking AUM. Flows calculated as change in index weight × tracking AUM. 

A wave of megacap IPOs could reshape index dynamics in ways that demand investor preparedness. While headline index weights may only shift modestly, the impact to investors would be felt through sector rotation, increased turnover and rebalancing flows. Concentration in high-growth sectors would accelerate capital into technology while sector-specific turnover would increase tracking error. Index inclusion could trigger substantial index-linked flows that may create significant liquidity and trading events. Managers should stress-test portfolios against multiple float scenarios now, to prepare portfolios against a potential IPO wave.