Vex: A FINRA-Regulated Trading Platform for Private Startup Stock, Amplified by AI

Trading Private Startup Equity, by the Book

Vex is building regulated infrastructure for private markets: a place where Qualified Purchasers can discover demand for, price, and trade equity in private startups.

Behind the product sit three regulated entities:

• Vex Securities LLC, a FINRA-registered broker-dealer operating the alternative trading system (ATS)
• Vex Registry LLC, an SEC-regulated transfer agent keeping the official ownership records
• Vex Holdings PR Corp, an SEC-registered investment adviser managing the fund vehicles that wrap each listed company

Vex Holdings engaged Pieoneers to build the investor-facing platform and back-office tooling. What followed was not one build but three. The platform moved from a database-centric architecture, through a planned migration to a GraphQL layer, to a from-scratch Go rewrite generated with Claude Code and brought to production standard by Pieoneers.

The decisions along the way are the real story: what to keep, what to abandon, and how to work when code arrives faster than any one person can review it.

How Pieoneers Built the Vex Trading Platform

Pieoneers built the investor web app in React 19 and TypeScript on Vite, with TanStack Router and Query, plus a separate admin app for Vex staff. The backend was a set of SQL modules (KYC, auctions, ledger, blockchain, transfer agent, notifications, admin) running on Omnigres (now Inferal), an innovative custom platform for products where data and security matter, developed in close collaboration with its founder Yurii Rashkovskii.

The team delivered the full investor lifecycle:

• Multi-step KYC with identity documents, W-9/W-8BEN tax certification, captured signatures and qualified-purchaser certification
• Dutch-auction bidding with superseding bids and partial outbids, auction finalization with clearing-price refunds and admin abort
• Crypto deposits via Tatum with wallet monitoring; wire withdrawals with routing, SWIFT and IBAN validation and CSV export
• Corporate accounts with multiple authorized representatives, sanctions.io screening and email notifications through Resend
• Transfer-agent cash and securities records, a daily reconciliation report, and two-admin approval of new investors

The platform reached AWS production after real-money test auctions, and Vex opened a private beta on vex.trade. The wire-deposit invoicing flow drew the client's most enthusiastic feedback and later became the reference for the reimplementation.

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What stands out most is their positive obsession with quality and precision. Their focus, discipline, and commitment to delivering the right solution often rival and surpass my own. The results speak for themselves: a strong product foundation, clear communication, and dependable execution.

As the product grew and pivoted, its needs changed. Vasiliy Reys, Pieoneers' lead engineer on Vex, documented what the next stage required: isolated schema migrations, a background job queue for webhook processing, and more flexible request middleware.

Pieoneers proposed a gradual path: introduce Hasura alongside the existing backend, move non-critical endpoints first, keep financial invariants such as ledger consistency and allocation correctness inside PostgreSQL, and extract orchestration and integrations into Go services. No big-bang rewrite.

The team quickly stood up a Turborepo monorepo with a Hasura DDN v3 app connected to the existing database, golang-migrate with a stamp-based workflow, a dedicated test container and transactional migrations. It was a credible path, and it was about to be overtaken.

In parallel, Vex co-founder and CEO Ryan Singer had been generating Go modules for a replacement platform with Claude Code. The first commits of "Vex ATS" included a design document, a git-backed transfer-agent core where markdown files serve as the official Master Shareholder Files, and a seven-step atomic delivery-versus-payment settlement engine. Close behind came the matching engine, passkey onboarding, KYC and a trading UI.

Vex asked Pieoneers to review it. Vasiliy's assessment was direct: the implementation looked strong, a few bugs had been found and fixed, some state drift between the git repositories and the Postgres cache remained, and it was an outstanding result for the effort involved. Pieoneers also asked the harder questions, including why holdings and balances should live in git at all. Ryan's answer was auditability; Yurii cautioned that a git-based ledger would not scale to efficient balance recalculation. Both perspectives went into the review.

The team made the call: the rewrite would replace the planned migration. Starting fresh was faster than carrying the old architecture forward, and the launch was anchored to the Vex Private Markets Summit.

Two operating rules followed. Every merge got a second approver: when Ryan merged, Pieoneers or Vex operations approved, and vice versa. And because one person cannot meaningfully review code produced at AI speed, Pieoneers used Claude Code itself to decode what had been built and to maintain living documentation alongside the code. That documentation now feeds Vex's Written Supervisory Procedures and compliance manuals.