Arcus security: audits, self-custody and what is not covered

Arcus security rests on four published things: two pre-launch audits, by OpenZeppelin on the rootchain contracts and by Trail of Bits in June 2026, a self-custodial design where Arcus says it never holds your funds or keys, a documented anti-MEV mechanism, and an insurance fund of unpublished size. No incident has been reported as of 2 October 2026.

The gap sits where you would most want a number. Arcus describes reserves as “intended to be publicly attestable”, which is an intention rather than an attestation, and there is no attestor, cadence or report to check.

The two audits

Arcus’ help centre points to two pre-launch audits with public reports. OpenZeppelin reviewed the Arcus rootchain contracts. Trail of Bits published a report dated June 2026, which lives as a PDF in the Trail of Bits publications repository.

Two named firms with published reports is a better position than most new venues manage, and it is worth being precise about what it buys you. An audit is a point-in-time review of a specific codebase by people who had limited time. It is not a guarantee, and it does not extend to code written afterwards.

That last point has teeth here. Both audits predate launch on 1 July 2026, and Arcus has shipped steadily since: USDG collateral on 21 July, Privy wallets on 22 July, the Fun funding integration on 29 July, doubled stock token markets on 11 August, pTokens on 26 August, isolated positions on 9 September, and the Robinhood Wallet RFQ integration on 1 October. Arcus has not published audit coverage for those additions. Isolated margin in particular is new accounting logic touching collateral, which is the kind of change you would want reviewed.

Self-custody, and the part it does not cover

Arcus says it never holds your funds or keys. Spot Stock Token trades settle wallet to wallet on Robinhood Chain. Perps collateral sits in Robinhood Chain contracts and, per Arcus, moves only under user-authorised conditions. Onboarding uses Privy embedded self-custodial wallets with email or social login and no seed phrase step.

What self-custody protects against is custodial failure. If Arcus Labs Ltd went under, a self-custodial design means there is no exchange balance to be frozen or clawed into an estate. That is a real benefit and it is the main thing people mean when they call a venue safer.

What it does not protect against is longer than what it does:

• Smart contract risk. Your assets sit in code. Audited code is still code.
• Issuer risk. Stock Tokens are issued by Bitstamp Global Ltd, which holds the underlying securities. Self-custody of a token says nothing about whether the share behind it is there, which is the subject of Arcus Stock Tokens.
• Market risk and liquidation. Self-custody has never stopped a position being closed out.
• Key and session loss. An embedded wallet with no seed phrase step removes a friction point and moves the recovery question into the login method you used.
• Jurisdiction. Arcus Labs Ltd is a Cayman Islands exempted company and the Terms are governed by Cayman law, last updated 30 June 2026. If something goes wrong, that is the venue.

The broader trust picture, including what could not be verified, is on whether Arcus is legit.

The anti-MEV mechanism

Arcus documents an anti-MEV mechanism. MEV, maximal extractable value, is what happens when whoever orders transactions can profit from that ordering, typically by front-running or sandwiching a trade they can see coming.

Arcus does not publish the full design, so how much protection it provides cannot be assessed from outside. The existence of a documented mechanism is a point in favour. Treating it as a solved problem would be going beyond what Arcus claims.

The insurance fund, and what happens when it is not enough

Arcus describes the insurance fund as a protocol-managed reserve that pays out counterparties for liquidations that would otherwise be unprofitable. In a fast move, a liquidated position can close below the price that would have made the counterparty whole, and the fund absorbs the difference.

Its size is not published. Without that figure there is no way to judge how large a shock it could take. Arcus does document what comes next: auto-deleveraging, where profitable positions are closed to balance the book, and socialised losses, where the shortfall is spread across traders. Those are the mechanisms that reach into a position you thought was safe, and they are explained on Arcus liquidations.

No incidents reported, which is not the same as none

No security incident, exploit or outage was found in any source checked as of 2 October 2026. Written honestly, that is “none reported”.

Two caveats belong with it. Arcus has been live since 1 July 2026, so the sample is three months long, and a short clean record is weak evidence either way. And an unreported incident is not necessarily an absent one, since there is no public incident page or status history to read. Where to check when something looks broken is covered on Arcus not working.

The proof-of-reserves gap

This is the one to take seriously. For a venue whose core product is a token that is supposed to be backed by a real share, proof of reserves is the load-bearing disclosure. Arcus says reserves are “intended to be publicly attestable”.

Intended. No attestor is named, no cadence is stated, and no attestation exists to link. So the backing of Stock Tokens currently rests on Bitstamp Global Ltd’s word and on Arcus repeating it.

If attestations arrive on a schedule from a named firm, that changes. Until then, treat the backing claim as unverified rather than audited, and size positions accordingly. For how this compares to other issuers, see tokenized stocks explained.

Who can use it, and the risk statement

Arcus is not available in the United States, the United Kingdom or Canada, plus other restricted jurisdictions named in the Terms, which also exclude sanctioned persons and comprehensively sanctioned regions and require you to be 18 or over. The full list is on Arcus countries.

Leveraged positions can be liquidated and most leveraged traders lose money. Stock Tokens are not shares: no voting rights, no dividend claim as such, not necessarily redeemable, and the price can diverge from the underlying. Nothing on this page is financial advice, and none of it comes from first-hand use. It is read from Arcus’ published documentation and the audit sources listed below as of 2 October 2026.