The number of U.S. public companies has halved from roughly 7,500 in 1995 to under 4,000 today according to CRSP data cited in the source tweet (Zywicki, 2025).

The original post states the statistic but omits sectoral patterns and causal literature. Doidge, Karolyi, and Stulz (Journal of Finance, 2017) document a persistent U.S. listing gap only partially explained by Sarbanes-Oxley compliance costs; rising intangible intensity in tech and improved private capital access via Rule 506 offerings account for the remainder (Coates & Srinivasan, Harvard Law Review, 2015). Coverage missed how venture and growth equity volumes rose from $20B annually in the mid-1990s to over $200B in recent years (NVCA Yearbook, 2024), enabling AI labs to remain private past $10B valuations.

Anthropic, xAI, and Inflection raised multibillion-dollar rounds without SEC-mandated 10-K or proxy disclosures on model training, safety evals, or cap tables, patterns synthesized from PitchBook unicorn delay data (2023) and Ritter IPO statistics (University of Florida, 2024). Public peers such as NVIDIA file quarterly risk factors on concentration and energy use; private counterparts do not.

The resulting capital-market structure prolongs founder and select-investor control of foundational AI systems, reduces mandatory public transparency on systemic risks, and shifts innovation accountability away from dispersed shareholders toward concentrated private boards.