The Vertalo Securities Protocol (VSP) is Vertalo's proprietary smart contract architecture for issuing and managing securities on-chain. Developed from Vertalo's own security token offering in 2018 — one of the earliest live deployments of a company tokenizing its own equity — VSP reflects the practical lessons of operating a compliant securities infrastructure at production scale across multiple chains.
VSP's distinguishing technical characteristic is its separation of concerns across four distinct smart contracts: PublicFront, PublicLogic, Roles, and Storage. The PublicFront contract is the investor-facing token interface; PublicLogic contains the transfer and compliance rules that govern every transaction; Roles manages access control across different operational functions; and Storage handles persistent state. This modular architecture allows individual components to be upgraded independently without deploying a new token. If transfer restriction logic changes to reflect a new regulatory interpretation, Vertalo updates PublicLogic. If investor role assignments change, Roles is updated. The token address — what investors see and interact with — remains stable across upgrades.
The role model is granular and maps deliberately to regulatory function. Three primary roles govern VSP token operations: the Owner, who controls administrative functions; the Transfer Controller, who manages investor eligibility and transfer approvals; and the Allowance Controller, who handles delegation and spending permissions. This functional separation mirrors the distinction that SEC transfer agent regulations impose between the entity that controls the cap table (the transfer agent) and the entity with economic authority over the shares (the issuer).
VSP's chain support is broader than most security token architectures. It operates in production on Ethereum, Tezos, and Aptos, with Vertalo functioning as an SEC-registered transfer agent across all three chains. The Tezos deployment in particular reflects real issuance volume and predates many other multi-chain tokenization efforts. That multi-chain capability matters for institutional issuers who want to reach different investor communities on their native chains, or who want the optionality of moving between chains without reissuing their securities.
Because VSP is proprietary and operated by Vertalo as a transfer agent service, the public documentation covers the architecture and contract responsibilities without exposing deployment-level implementation details. VSP sits in a distinct category from open standards like ERC-7943 or ERC-3643: it is a production-grade, regulatory-compliant infrastructure operated by a registered transfer agent, not an interface specification that third parties can implement independently. That is a feature for issuers seeking a managed service with a known regulatory counterparty. It is a constraint for platforms seeking full technical independence.
Technical Specification
The Vertalo Securities Protocol (VSP) is Vertalo's proprietary multi-chain smart contract architecture for issuing, managing, and transferring compliant securities on-chain. Vertalo is an SEC-registered transfer agent. VSP is not submitted as an EIP or open standard. The following is derived from Vertalo's public API documentation and published technical materials.
ARCHITECTURE: FOUR-CONTRACT SEPARATION OF CONCERNS
PublicFront
The externally-facing token contract. This is the address that investors interact with,
that wallets display, and that appears in investor records. PublicFront is intentionally
thin — it delegates execution to PublicLogic for all substantive operations.
Role: public interface and address stability across upgrades.
PublicLogic
Contains the business logic for all token operations: transfer rules, compliance checks,
freeze logic, and forced transfer authorization. PublicLogic is upgradeable — Vertalo
can replace the logic contract without changing the token address visible to investors.
Role: compliance and transfer rule engine.
Roles
Access control registry. Defines which addresses hold which operational roles and
enforces access control on all privileged functions.
Role: authorization and permission management.
Storage
Persistent state contract. Holds token balances, allowances, frozen amounts, and
other state that must survive logic upgrades. By separating state from logic,
Vertalo can upgrade PublicLogic without migrating balances.
Role: durable state store.
ROLE MODEL
Owner
Administrative authority over the token. Sets contract configurations, updates
role assignments, and controls the logic and storage contract addresses.
Maps to: issuer or Vertalo administrative function.
Transfer Controller
Authority to approve or reject individual transfers, update investor allowlists,
and manage transfer restriction parameters. This role carries the functional
authority of a registered transfer agent: knowing who holds what, approving
ownership changes, and maintaining the official book of record.
Maps to: SEC-registered transfer agent function.
Allowance Controller
Authority to set and manage spending allowances — delegated transfer rights.
Enables broker or custodian relationships where a third party is authorized to
transfer tokens on behalf of an investor within defined parameters.
Maps to: broker/dealer or custodian delegation model.
TRANSFER RESTRICTION MECHANISM
Transfers are subject to allowlist-based access control:
- Both sender and recipient must be on the active allowlist (Vertalo's investor registry)
- Allowlist is maintained by the Transfer Controller based on KYC/AML and accreditation status
- Frozen balances cannot be transferred; freeze state is maintained in Storage
- Transfer Controller can perform forced transfers for corporate actions, court orders,
or error recovery — the primary forced-transfer mechanism
- The allowlist is updated off-chain (investor completes KYC through Vertalo's platform)
with on-chain enforcement at the moment of transfer
CHAIN SUPPORT (PRODUCTION)
Ethereum: primary chain for US institutional issuances; Solidity implementation
Tezos: significant production deployment history; SmartPy/Michelson implementation
Aptos: newer deployment; Move language implementation
Each chain has a native implementation of the four-contract pattern in the chain's
native language. There is no cross-chain token bridge in VSP — each chain deployment
is an independent token representing the same security, with Vertalo as the common
transfer agent maintaining a unified cap table across chains.
UPGRADE PATTERN
VSP's four-contract architecture enables targeted upgrades:
- PublicLogic upgrade: deploy new logic contract, update PublicFront to point to it.
Investor-visible address unchanged. Balances in Storage unaffected.
- Roles upgrade: update role assignments without touching token logic or state.
- Storage migration: the most disruptive upgrade; rarely required if Storage is stable.
This is VSP's clearest architectural advantage over ERC-3643 (which requires token
migration for major changes) and ERC-1400 (no built-in upgradeability).
REGULATORY STANDING
Vertalo is a registered transfer agent under SEC regulation. This means:
- Vertalo's books and records are subject to SEC examination
- The Transfer Controller function is exercised by a regulated entity
- Cap table records maintained by Vertalo are legally authoritative for US securities
- Investor accreditation and KYC records are maintained in forms consistent with
SEC compliance expectations
Vertalo's origins in its own 2018 STO means VSP was battle-tested against real
regulatory scrutiny before being offered to third-party issuers.
DOCUMENTATION NOTE
Public documentation at api.vertalo.com covers the architecture and API endpoints
for integration. Smart contract source code and detailed function signatures are
not publicly published. Independent technical audit requires access to Vertalo
as a business partner.
Key Features
Four-contract separation of concerns: PublicFront / PublicLogic / Roles / Storage enables targeted upgrades without token migrationSEC-registered transfer agent operation: Vertalo holds the regulatory credential that makes Transfer Controller functions legally authoritative for US securitiesMulti-chain production deployment: Ethereum, Tezos, and Aptos — the broadest chain support of any transfer-agent-operated platform in this surveyGranular role model: Owner / Transfer Controller / Allowance Controller maps directly to regulatory functional separation between issuer, transfer agent, and brokerUpgradeable compliance logic: PublicLogic can be replaced to reflect regulatory changes without changing the investor-visible token address or migrating balances
US Regulatory Fit
VSP is purpose-built for US securities regulatory compliance. Vertalo is an SEC-registered transfer agent, which means the Transfer Controller role in VSP is exercised by an entity with the legal authority to maintain the official book of record for US securities under Section 17A of the Securities Exchange Act. This is the clearest regulatory alignment of any standard in this survey: the transfer restriction mechanism is operated by a registered transfer agent, investor records are maintained to SEC examination standards, and forced transfers are executed by an entity with the legal authority to do so. VSP supports Regulation D, Regulation A, and Regulation S exempt securities, with accreditation verification and holding period enforcement built into Vertalo's investor onboarding workflow. The multi-chain capability means issuers can issue on Ethereum (where US institutional investors and custodians are most comfortable) or on Tezos or Aptos depending on their investor base. Unlike DS Protocol, Vertalo does not operate its own ATS for secondary market trading, which is both a limitation (no integrated secondary market) and a flexibility advantage (issuers can work with multiple ATS providers). Vertalo's origins in its own 2018 STO means VSP was stress-tested under real regulatory conditions before being offered to third parties.
Institutional Adoption
Vertalo's platform has facilitated tokenized securities issuances since 2018, making it one of the longest-operating security token transfer agents in the US market. Notable use cases include: real estate fund tokenization for platforms using Vertalo as the back-office transfer agent; private equity fund interests for emerging market issuers; and digital asset fund structures on Tezos where the Tezos ecosystem provided early tokenization infrastructure. Vertalo has been particularly active in the real estate and alternative investment space rather than the large-cap institutional product segment that Securitize occupies. The Tezos deployment history is meaningful: Tezos was an early chain for institutional tokenization, and Vertalo's multi-year production operation on that chain represents genuine operational expertise across non-EVM architectures. The Aptos deployment reflects Vertalo's commitment to chain-agnostic operations as the multi-chain landscape evolves.
Limitations & Trade-offs
Proprietary architecture: no public interface specification, no independent implementation path, limited technical due diligence without a business relationshipTransfer agent dependency: the Transfer Controller role requires Vertalo to remain operational; the token governance cannot be transferred to a different transfer agent without migrationNo community ecosystem: unlike ERC-7943 or ERC-3643, there is no third-party tooling, auditor pool, or developer community around VSPLimited public documentation: contract-level implementation details are not publicly available; due diligence relies on Vertalo's representationsSmaller institutional client base than Securitize/DS Protocol in the US large-cap institutional segment as of 2025