May highlights: Private market momentum builds behind AI and IPO hopes
Private market benchmarks strengthened meaningfully in May, with gains outpacing public market indices. The equal-weighted Forge Private Market Index (FPMI) rose 11.73%, while the cap-weighted Forge Accuidity Private Market Index (FAPMI) gained 12.58%. Public equities were also positive, with SPY up 5.26% and QQQ rising 10.57%.
May represented a potential market regime change for private companies, as secondary market performance converged with a rapid shift toward public market disclosure: Cerebras (+174.07%) priced its IPO,1 Anthropic (+122.63%) confidentially submitted a draft S-1 shortly after month-end2 and SpaceX (+3.43%) made its S-1 publicly available.3
The gains were powerful but still concentrated. Performance was led by the Forge Chips and Artificial Intelligence (AI) thematic baskets, with AI infrastructure and frontier AI platforms driving gains, while Consumer was the only basket to decline.
Benchmarks rose, but leadership stayed narrow
Anthropic was the largest visible contributor to FAPMI, adding 7.62% to the benchmark and 20.35% to the AI basket. The move came in a month when Anthropic announced a $65 billion Series H financing at a $965 billion post-money valuation,4 followed shortly after by a confidential draft S-1 submission to the SEC.5
Cerebras was the clearest driver of performance for the month, adding 9.03% to FPMI, 2.51% to FAPMI, 7.63% to the AI basket and 111.40% to the Chips basket. Cerebras priced its IPO at $185 per share, above the earlier $115-$125 indicated range, and the shares began trading on Nasdaq under the ticker CBRS on May 14, ultimately closing its first day of trading around $311 per share.6 Its debut set an important reference point for private AI infrastructure valuations.
SpaceX also added support, contributing 0.58% to FAPMI and 1.51% to the Aerospace & Defense (A&D) basket after its S-1 became publicly available during the month. Lightmatter (+61.23%) was another standout, adding 1.21% to FPMI and 35.56% to the Chips basket, reinforcing the month's concentration in AI infrastructure and semiconductor-linked private names.
Several decliners limited the breadth of the move. Addepar (-27.14%) subtracted 0.51% from FPMI and 0.70% from the Fintech basket. Replit (-27.27%) weighed on the AI basket, while Epic Games (-16.83%) detracted from both FPMI and the Consumer basket.
AI infrastructure carried the thematic scoreboard
The Chips basket rose 136.94% in May, by far the strongest thematic return. Cerebras was the primary driver, while Lightmatter added 35.56% to the basket. PsiQuantum (-8.12%) was the main offset, subtracting -10.02%.
The AI basket gained 30.55%. Anthropic, Cerebras, Databricks (+14.61%) and OpenAI (+2.54%) supported the theme, while Replit and several smaller decliners reduced the overall return.
The A&D basket rose 2.10%. SpaceX contributed 1.51%, while Shield AI (+3.63%) added 0.41%. SpaceX's public IPO filing in May added another private market reference point for investors evaluating the path from large-scale private company pricing to public market scrutiny.
The Consumer basket fell -9.39%, making it the clear laggard. Eight Sleep (+39.41%) was positive, but the basket was pressured by WHOOP (-43.19%) and Epic Games.
The Fintech basket gained 1.47%. Kraken (+15.34%), Ripple (+9.26%) and Mercury (+22.21%) helped offset weakness from Addepar, Polymarket (-5.85%) and Ramp (-1.98%). Kraken's parent, Payward, was reportedly seeking new capital at a $20 billion valuation ahead of a planned IPO.7
The IPO queue begins to dominate the story
Cerebras provided the first live test of investor appetite for the current AI infrastructure pipeline, as its first day close at $311.07 dropped to $ 214.94 by early June.8 That pattern matters for late-stage private markets because it showed both the depth of demand for differentiated AI infrastructure and the speed with which investors can reprice newly listed names once scarcity gives way to daily liquidity.
SpaceX's filing widened that discussion beyond near-term price action. The S-1 showed a company still carrying large losses, with TechCrunch reporting a roughly $4.9 billion 2025 loss on more than $18 billion of revenue and more than $37 billion of cumulative losses since inception.9 At the same time, Starlink generated more than half of 2025 revenue, or roughly $11 billion, while the filing continued to frame Starship around Mars, reusable heavy-lift launch, next-generation Starlink deployment and orbital AI data-center ambitions.10 The tension is central to the investment case: Starlink is helping fund a much broader set of ambitions, while the scale of losses and capital intensity make SpaceX a test of how much long-duration frontier infrastructure investors are willing to underwrite.
Anthropic and OpenAI now sit in the same conversation. The two frontier AI companies are both approaching trillion-dollar valuations prior to their anticipated fall debuts, before investors have even had a chance to conventionally review their margins, compute obligations and capital requirements. The bullish counterpoint is equally important: OpenAI has described itself as core infrastructure for consumer, enterprise, developer and compute-driven AI adoption,11 while Anthropic said enterprise adoption continued to expand and run-rate revenue crossed $47 billion in May.12 Both companies are also building deployment muscle around their models: OpenAI launched a forward-deployed engineering company to help enterprises redesign workflows around AI, while Anthropic has moved to expand its own enterprise deployment ecosystem, underscoring that frontier AI adoption is increasingly being sold as an implementation-led transformation rather than a software license alone.13
May’s rally was strong, selective and shaped by IPO momentum
Taken together, May marked a stronger and more concentrated advance than April. Amid the IPO storm, FPMI rose 11.73% and FAPMI gained 12.58%, while Forge’s Chips and AI led thematic basket performance and select fintech names added support. Yet Forge’s Consumer basket weakness and several sharp company-level decliners reinforced that private market performance continues to be shaped more by issuer-specific catalysts than by broad beta alone.
