Bank of America strategist Michael Hartnett issued a stark warning on May 22. Anticipated mega IPOs from SpaceX and OpenAI could push technology’s share of major equity benchmarks beyond dangerous levels. The strategist warned that tech concentration could exceed 48% of the S&P 500 Index. That threshold matches historical market bubbles that ended painfully.

Elon Musk’s SpaceX has filed plans for one of the world’s largest initial public offerings. The company targets a valuation north of $1.75 trillion. It aims to raise up to $75 billion in capital. A potential Nasdaq debut could arrive in June. Meanwhile, ChatGPT maker OpenAI prepares a confidential IPO filing. Its most recent private valuation hit $830 billion following a massive funding round.

The S&P 500 Index already carries a significant tech weighting, exceeding 44%. The addition of two massive new listings threatens to push the tech weighting in the S&P 500 Index even higher. Combined valuations from both companies exceed $2.5 trillion. That scale would concentrate the index further in a sector that already dominates.

Historic Bubble Comparisons Draw Attention

Hartnett drew explicit comparisons to infamous market episodes. He referenced the Roaring ’20s and the Nifty Fifty era of the 1970s. He also cited Japan in the 1980s and the TMT bubble of the 1990s. All these periods featured narrow market leadership that eventually collapsed. Investor enthusiasm around narrow stock groups created concentration risks. History shows these risks eventually materialized.

The strategist described current market conditions as “so bubbly.” He pointed to strong price action, retail investor mania, and slumping volatility. These indicators typically appear during late-stage bull markets. The pattern mirrors previous bubble periods. In these periods, few stocks drive most gains. Broader markets lag behind.

Stock indexes heavily slanted toward surging tech sectors carry hidden dangers. They potentially mask weaknesses lurking beneath the surface. Sectors more directly tied to the economy face headwinds. Consumer stocks and financial stocks show less enthusiasm from investors.

Passive Fund Problem Amplifies Risk

If SpaceX and OpenAI gain rapid inclusion in benchmark indices after listing, passive funds face forced buying. These funds must purchase large amounts of shares in compressed timeframes. That forced buying amplifies demand regardless of valuation. Prices get pushed higher automatically. Tech’s overall weighting increases even further through this mechanism.

Asset allocators face particular challenges from rising concentration. Risk management constraints prevent them from fully tracking these weightings in portfolios. Portfolio managers must decide whether to deviate from benchmarks. Both choices carry career risk. Underweighting tech means missing rallies. Overweighting means excessive concentration exposure.

Bond Yields Hold Key to Bubble Resolution

According to Hartnett, a surge in bond yields ends booms and bubbles. The strategist correctly predicted international equities’ outperformance last year. His bullishness on commodities also paid off. He now identifies specific markers for tracking yield impacts on markets.

Hartnett highlighted two State Street exchange-traded funds as twin indicators. A drop in the biotech ETF to $120 would signal continued bond yield surges. Biotech names typically serve as speculative market barometers. If the retail stocks ETF rises to $85, that suggests postponement of bond-related shocks.

Past IPO Patterns Offer Mixed Signals

Hartnett reviewed major IPO debuts from recent history. Offerings like Saudi Aramco and Meta Platforms proved inconsequential for broader stock markets. In some cases, markets fell within 9-12 months after “toppy” offerings. Visa and AIA Group both preceded market weakness.

The gigantic share sales would feed into optimism around tech and artificial intelligence. That enthusiasm already powers one of the narrowest rallies in decades. Market breadth remains concerningly weak despite headline index gains.

Harbor Funds Launch AI Lab ETFs

Harbor Capital Advisors filed with the SEC for five new exchange-traded funds. Each fund tracks the commercial ecosystem surrounding a single private AI laboratory. The funds would trade on NYSE Arca. They represent one of the most direct attempts to let everyday investors access the AI wave.

The five proposed products include the Anthropic AI Lab ETF, Google DeepMind AI Lab ETF, and Meta AI Lab ETF. Also planned are the OpenAI Lab ETF and xAI AI Lab ETF. Each uses an actively managed structure. Portfolio managers will pick and weight holdings rather than tracking an index passively.

Ecosystem Exposure Solves Private Access Problem

Most AI labs driving the current technology cycle remain private. OpenAI, Anthropic, and xAI lack publicly traded shares. Google DeepMind sits inside Alphabet. Meta AI embeds within Meta Platforms. Pure research arms themselves remain separately uninvestable.

Harbor’s workaround targets each lab’s “ecosystem.” Rather than buying shares in labs directly, funds hold publicly traded companies. These companies have products, partnerships, or revenue streams tied to specific lab technology. Examples include cloud providers running inference for OpenAI. Chipmakers supply training clusters for Anthropic. Enterprise software firms embed specific lab models into their products.

The filing landed on May 22, 2026, under the Harbor ETF Trust. All five funds would list on NYSE Arca. The exchange already hosts the bulk of US-listed ETFs.

Market Evolution Brings New Access and Risk

Harbor previously launched the Harbor AI Inflection Strategy ETF, trading under ticker EPAI. That product took a broader approach to AI exposure across sectors. The Lab ETFs represent deliberate narrowing of focus. Instead of one fund covering the entire AI landscape, Harbor slices the market into five distinct bets.

The actively managed structure means higher fees compared to passive index funds. Harbor has not yet disclosed expense ratios. Investors face reliance on portfolio manager judgment. Manager skill becomes critical for outperformance versus benchmarks.

AI investing is moving from venture-only territory to public markets. This shift expands retail access dramatically. That democratization carries both risks and opportunities. Retail investors gain exposure to cutting-edge technology. But they also inherit volatility and concentration risk previously confined to venture portfolios.

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