Definition
An Alternative Trading System (ATS) is an SEC-regulated electronic trading venue that brings together buyers and sellers of securities and executes trades, but does not qualify as a national securities exchange. The ATS framework was established under Regulation ATS (17 CFR §§ 242.300-303), adopted in 1998 and substantially amended in 2018, which allows trading systems to operate either as broker-dealers with a Form ATS filing on record with the SEC or as national exchanges with full exchange registration. ATS operators must be registered broker-dealers, maintain FINRA membership, and operate under the SEC’s alternative trading system rules, which include requirements for fair access (above certain volume thresholds), operational transparency, systems capacity and integrity standards, and recordkeeping. Unlike national exchanges, ATSs are not required to publish real-time quotation data, may restrict access to a defined subset of investors (such as accredited investors only), and operate under less prescriptive market structure rules.
For tokenized securities, the ATS framework is the primary legal mechanism for secondary market liquidity. Securities sold under Regulation D are “restricted securities” that may not be freely resold for 6 to 12 months, and after that period they can only be resold under an exemption or a new registration — with SEC-registered ATS transactions qualifying as an exemption under Rule 144A (for large transactions) or as registered exchange transactions on an ATS. The practical effect is that any investor who purchases a tokenized security and later wishes to sell must find a counterparty through an SEC-registered ATS operated by a FINRA-member broker-dealer. There is no other legal venue for secondary trading of most US digital securities.
Key Facts
- As of early 2026, more than 12 ATSs are registered specifically for digital securities trading, including tZERO (owned by Overstock), MERJ Exchange, INX, Texture Capital, and others.
- The total ATS landscape in the US includes approximately 40-50 active ATSs across all asset classes, with dark pools (institutional equity) comprising the majority by trading volume.
- Form ATS must be filed at least 20 days before the ATS commences operations; material changes require 20-day advance notice filing with the SEC.
- ATS operators trading a National Market System (NMS) stock must comply with Regulation ATS’s fair access requirements if they exceed 5% of average daily volume in any NMS stock.
- The SEC’s 2020 proposed amendments to Regulation ATS would require ATSs trading government securities to register as broker-dealers and file Form ATS-N — extending oversight to the Treasury market.
- The 2022 SEC proposal to expand Regulation ATS to cover US Treasury security ATSs reflects the SEC’s concern about opacity in the $26 trillion Treasury market and would impose additional requirements on platforms trading tokenized Treasuries.
- tZERO, the first SEC-registered ATS for digital securities, launched in 2019 and facilitates secondary trading of security tokens issued under Reg D and Reg A+, with settlement on a proprietary blockchain ledger.
Relevance to Tokenization
The ATS framework is the structural foundation of the US tokenized securities secondary market, and its limitations significantly constrain the liquidity promise that tokenization advocates make. Tokenization theoretically enables 24/7 global trading, instant settlement, and frictionless liquidity — but the legal requirement that all secondary trading of tokenized US securities occur through an SEC-registered ATS subjects that trading to market hours limitations, investor eligibility verification requirements, and regulatory oversight that reduces the efficiency advantage over traditional securities markets.
The accreditation verification requirement in secondary trading is a particular friction point. Even after a Reg D token’s 12-month restriction period expires, sellers can only transfer their tokens to new investors who have been verified as accredited — meaning the ATS must maintain an active KYC/AML and accreditation verification process for all buyers, not just initial purchasers. This requirement dramatically shrinks the available secondary market compared to a truly public market, limits the liquidity premium that tokenization can deliver, and imposes ongoing compliance costs on the ATS operator that traditional exchange operators do not bear.
The solution most commonly discussed is the development of a regulatory pathway for tokenized security ATSs to serve a broader investor pool — either through expanded Reg A+ secondary markets (where tokens are freely tradeable) or through a proposed retail digital securities trading framework. Several tokenization platform operators have engaged with the SEC’s Crypto Task Force in early 2025 to explore an ATS framework specifically designed for tokenized securities that would incorporate on-chain compliance verification to reduce the operational burden of investor eligibility checking, potentially enabling more efficient secondary markets while maintaining appropriate investor protections.
Related entries: Broker-Dealer Registration, Regulation D, Security Token