规模估算高度分歧。FSOC近年指出缺乏完整资料，SEC于2023年估计CIT规模约7万亿美元（US$7tn）；Cerulli Associates后续估计2024年末约6万亿美元（US$6tn）。Gary Gensler在2023年的发言中称，联邦登记信托约有5万亿美元（US$5tn），另约2万亿美元（US$2tn）由州授权信托管理，但州级披露标准不一，马萨诸塞州与宾州部分档案甚至可免公开披露。Morningstar虽接收部分管理人资料，仍受自愿性上报与内嵌信托重复计算干扰，估计完整性有限。BlackRock联邦申报的CIT资产约1.37万亿美元（US$1.37tn），但三大行业资料供应商估算仅为4,670亿至9,740亿美元，差距源于是否纳入确定福利与确定缴费计划、以及汇整口径差异。缺乏集中监管主体让行业总规模与变化趋势难以精准量化。
倡导者认为CIT的核心优势在于成本和客制弹性。根据Morningstar对2023年的分析，CIT在主动与被动策略下平均成本少于共同基金的一半，并可设计专属份额类别以依计划规模协商费率；因此资产管理人可持续吸引退休计划。支持方并指出CIT受ERISA、DOL与银行监管，并非缺乏监管；反对方则认为这是监管套利，与SEC对共同基金的标准不一致。监管分歧还涉及流动性与治理，CIT不必具备同等日常揭露机制，亦不必每日报价、公开章程或完整投票披露。2025年目标日期共同基金转入CIT金额达543亿美元（US$54.3bn），为2022年后最大的一季；CIT目前持有美国最大上市公司资产约3%–5%。若以CIT作为引入私募市场通道，可能使私有资产在定义缴费型（DC）退休体系中的渗透由2023年的不足0.5%（基于$8万亿美元）快速推升至接近已在定义给付制中17%水平的量级，形成万亿美元级别潜在再分配风险。
Collective Investment Trusts (CITs) are now a core vehicle in US retirement planning despite limited public visibility. In 401(k) plans with more than 100 participants, CITs reached about 40% of assets in 2024, up from 12% in 2010, and above the share in mutual funds. They are favored as a lower-cost wrapper: DOL data show that 401(k) plans with over $1 billion had close to 50% in CITs, while $100 million to $1 billion plans were around 30% and rising. Proposed 403(b) access, on top of policies promoted under President Donald Trump, could open roughly $1.5 trillion in additional retirement pools to CITs and amplify this shift.
The size of the market remains hard to pin down. The Financial Stability Oversight Council has warned of limited data; the SEC in 2023 estimated around $7 trillion, while Cerulli Associates later put 2024 Q4 holdings near $6 trillion. Gary Gensler cited roughly $5 trillion federally registered and about $2 trillion in state-chartered trusts, but reporting differs by state and can be nonpublic in places like Massachusetts and Pennsylvania. Morningstar receives some manager reporting, yet acknowledges limitations from voluntary disclosure and double-counting when trusts hold each other. BlackRock reports $1.37 trillion under federal filing, but major industry providers estimate only $467 billion to $974 billion depending on methodology. Without a central regulator, aggregate totals and trend tracking remain unstable and hard to compare across time.
Supporters emphasize cost and design flexibility: Morningstar’s 2023 study found CITs cost less than half as much as mutual funds on average, and bespoke share classes help large plans negotiate lower fees. Defenders say ERISA, DOL, and banking regulators provide adequate safeguards; critics call it regulatory arbitrage versus the SEC fund model. Lower disclosure requirements mean less public visibility, weaker liquidity and governance transparency. In 2025, $54.3 billion in target-date mutual fund assets moved into CITs, the largest annual migration since 2022, while CITs now hold about 3%–5% of major US equities. Private assets were under 0.5% of $8 trillion defined-contribution plans in 2023 versus 17% in defined-benefit plans, so routing private markets through CITs could drive a potentially trillion-dollar reallocation with limited public oversight.