USTB — Invesco Short Duration US Government Securities Fund

USTB is one series of the Superstate Asset Trust, a Delaware statutory trust ("DST") organized in series and formed on 26 October 2023. The fund is governed by its Sixth Amended and Restated Declaration of Trust and Trust Agreement, dated 1 June 2026. The series structure is material: under the Delaware Statutory Trust Act ("DSTA"), the assets and liabilities of each series are maintained separate from every other series, so USTB's portfolio is insulated from the obligations of any other series of the Trust.

The fund is a private fund, not a registered investment company. It relies on two exemptions: Section 3(c)(7) of the Investment Company Act of 1940 (exclusion from registration as an investment company, available where all investors are Qualified Purchasers), and Rule 506(c) of Regulation D (exemption from securities registration). Accordingly, USTB is offered only to Accredited Investors and Qualified Purchasers and is not registered for public exchange trading. Investors transact against the offering materials (PPM and Investment Agreement).

A USTB token represents a direct legal interest in fund shares, not a synthetic, derivative, or wrapped claim on a third party. Shares are issued either as Book Entry Shares or as Tokenized Shares; Tokenized Shares are recorded on the fund's Designated Blockchains and are the same security as the book-entry form. There is no intermediating SPV or feeder between the investor and the fund: the investor is a shareholder of the series, the series owns the Treasury Bills, and the bills sit with the custodian. This is a structurally cleaner arrangement than wrapper- or SPV-based tokenized products, in which the on-chain token is one or more legal steps removed from the underlying assets.

Effective 1 June 2026, Superstate Advisers LLC ceased to serve as Investment Manager and Invesco Advisers, Inc. assumed day-to-day portfolio management (per the PPM, and corroborated by the March 2026 Invesco–Superstate announcement). Invesco Advisers is a Delaware corporation, SEC-registered as an investment adviser since 1988, and an indirect wholly-owned subsidiary of Invesco Ltd. (NYSE: IVZ), an S&P 500 constituent and one of the largest global asset managers. There is no sub-adviser in the current structure. The fund is managed by Invesco's Global Liquidity team, with named portfolio managers Laurie Brignac, CFA and Marques Mercier. The fund's investment strategy, structure, ticker, smart contracts, and token address are unchanged through the transition; Superstate continues to operate the on-chain infrastructure as transfer agent. The fund has been renamed the Invesco Short Duration US Government Securities Fund, and maintains its original token symbol, USTB.The transition is a credibility upgrade in service-provider quality — a large, well-resourced, long-established manager — but it does not alter the fund's risk architecture, governance terms, or the discretionary powers discussed in the governance section.

The custody, audit, and NAV-calculation functions — the three most important for asset integrity and valuation — are performed by independent, top-tier providers. The non-independent roles (placement, liquidity provision, counsel) are disclosed and structurally typical of the private-fund format.

Fund assets are insulated from the insolvency of the Investment Manager. USTB owns its portfolio (Treasury Bills, cash, and USDC), and that portfolio is held by an independent custodian, BNY Mellon. The Investment Manager manages but does not own or take custody of fund assets; in an Invesco insolvency, Invesco's creditors would have no claim on assets that sit on the custodian's books rather than the manager's balance sheet.The management relationship is contractual and replaceable. The Investment Management Agreement is terminable by either party on 30 days' written notice, and a successor manager can be appointed under the Trust Agreement, allowing the fund to continue operating through a management gap. As a practical backstop, the portfolio consists entirely of short-dated bills that self-liquidate to cash at maturity in the custody account, independent of the manager's continued operation. At the series level, the DSTA interseries limitation of liability separates USTB's assets and liabilities from every other series of the Trust — though this statutory limitation is judicially untested, and a court could in principle recognize equitable exceptions in an insolvency.

The Investment Manager holds broad discretionary authority over fund operations. The principal powers are summarized below.

The Fund Documents describe the Investment Manager's and Transfer Agent's rights and obligations with respect to redemptions, transfer restrictions, allowlist controls, and remediation procedures. Transfers of tokenized shares are subject to allowlist controls, and completed transfers to allowlisted wallets are not unilaterally reversed by Superstate.

The mandate is narrow and conservative:

• Eligible instruments: substantially all assets in U.S. Treasury Bills; assets not in Treasuries held in cash. The fund also holds USDC for on-chain settlement. No direct or indirect exposure to assets relying on blockchain technology other than USDC.
• Minimum allocation: at least 95% to U.S. Government Securities and Treasury-collateralized repo under normal conditions.
• Maturity: target weighted-average portfolio duration of 6 months or less; individual purchases limited to fixed- and floating-rate securities with a final maturity or demand feature of 190 days or less.
• Issuer concentration: the portfolio is single-issuer by design (the U.S. Treasury), so issuer-concentration limits are not the binding constraint they would be for a credit fund; the binding constraints are maturity and the per-security cap.
• Distributions: none — income is reinvested and reflected in a rising NAV per share rather than paid out.

The Investment Manager does not employ investment leverage. The only borrowing is redemption-facilitation borrowing under the Liquidity Facility, capped at $10M of outstanding principal. The mandate permits Treasury-collateralized repo within the 95% government-securities bucket, but the current book is composed of outright bill holdings rather than repo overlays. There is no securities-lending program disclosed against the portfolio. Custody at BNY Mellon, with the fund as direct owner, is the structural protection against rehypothecation of the underlying bills.

Maturity ladder:

All 13 positions are U.S. Treasury Bills issued by the U.S. Department of the Treasury, with no deviation from the eligible-instrument scope. The longest remaining maturity (≈90 days) sits well inside the 190-day per-security limit, and the ≈32-day WAM sits comfortably inside the 6-month mandate. The ladder is front-loaded — roughly 52% of the book matures within 30 days, declining across longer buckets — which is consistent with normal roll-cycle dynamics for a short-duration laddered Treasury fund and is a liquidity positive: large balances self-liquidate to cash within weeks regardless of manager action.

The fund operates a two-layer NAV: a daily authoritative valuation and a continuous interpolated price.

Treasury Bills are valued using a straight-line discount amortization (amortized-cost) method: each day between purchase and maturity, the fund recognizes one day's worth of the discount as income, and expenses are recognized daily. This produces a smooth, monotonically increasing NAV per share under normal conditions and explains why the fund has never recorded a NAV/share drawdown to date. Amortized cost can, in principle, diverge from mark-to-market in a sharp rate move, but the divergence is bounded and small for a portfolio with a low WAM.

Pricing reaches the chain through two parallel feeds, both ultimately derived from Superstate's NAV/share calculations (which themselves derive from NAV Consulting's daily calculation):

• Superstate USTB Continuous Price Oracle — a verified SuperstateOracle implementing Chainlink's AggregatorV3Interface. It stores daily NAV/share checkpoints and computes a real-time price by linear extrapolation between the two most recent valid checkpoints. It enforces a 5-day staleness window (CHECKPOINT_EXPIRATION_PERIOD) past which it reverts with StaleCheckpoint, and a per-checkpoint price-delta bound (maximumAcceptablePriceDelta) that rejects any new checkpoint deviating from the prior one beyond a configured tolerance. This oracle powers atomic subscriptions and redemptions through the protocol mint/redeem functions.
• Chainlink USTB Oracle — a Chainlink-operated EACAggregatorProxy ("Chainlink: USTB NAV per Share Feed") that publishes NAV per share on-chain once per day, sourcing data from the Superstate API. It runs in parallel to, not downstream of, the Continuous Price Oracle and provides the canonical price reference for external integrators.

Lag and queryability. NAV per share is queryable directly on-chain via the oracle contracts and via the Superstate API. The authoritative Market Day NAV is struck at the 5:00 PM ET snapshot and published on-chain by 9:07 AM ET the following market day; intraday, the Continuous NAV updates per second by extrapolation. The deviation and staleness guards on the oracle are the primary on-chain safety controls against a bad or stale price entering a value-moving transaction.

Yield accrues continuously (intraday), not only at end-of-day: because the Continuous NAV updates per second by extrapolating accrued income, a depositor begins earning from the moment of subscription, with no wait for a daily cut-off, and the same continuous price governs both deposits and withdrawals. There are no distributions; return is realized through NAV appreciation. The fund has not suffered a NAV/share drawdown to date. Life-to-date performance and 30-day yield are published on the fund page and via the API; the published 30-day yield is net of fees and expenses.

The Superstate's operating team benchmarks gross income against independently published 7-day net yield (plus an approximate 20bps gross-up for fees) within a ±5bps tolerance, and validates the expense ratio against the expected 15–25bps fee range. Any figure outside these thresholds raises a break flag. The oracle contracts independently enforce their own boundary and stale-data checks. NAV Consulting calculates from custody data but relies on those inputs without independent verification. On this basis, the controls that matter most are the custodian's record integrity and the oracle's deviation/staleness guards.

Subscriptions and redemptions are available through Superstate's interface, API, and — for Tokenized Shares on Ethereum — directly via the smart contract's Protocol Mint and Protocol Redeem functions. On Ethereum, subscriptions and redemptions within the on-chain buffer are atomic: a single transaction mints or burns USTB against USDC at the Continuous NAV. All counterparties must be on the fund's allowlist; transactions involving non-allowlisted addresses revert. There are no caps on redemption frequency or maximum size.

The fund processes liquidity through two daily "Cash Needs" windows, at approximately 9:00 AM and 1:00 PM ET each market day (per fund operational documentation). Same-day liquidity is uncapped in practice: a redemption of any size submitted before a window is reviewed the same day, typically within a few hours. The Private Placement Memorandum and Investment Agreement bind the team to a T+2 maximum settlement period; given the short-duration T-Bill portfolio, this is not a practical constraint, and the team is mandated to settle within T+2 with no discretion to extend except in extreme scenarios. No redemption has ever been suspended to date.

A standing USDC buffer (up to ~$10M), held in the USTB RedemptionIdle contract, backs atomic on-chain redemptions: a holder redeeming within available buffer capacity burns USTB and receives USDC directly from this contract in a single transaction, and the call reverts if the buffer is insufficient. The buffer is replenished during the two daily Cash Needs windows as USD redemption proceeds from BNY Mellon are converted back to USDC. Outstanding buffer capacity is observable directly on-chain via the contract's USDC balance — the primary monitoring signal for instant-redemption capacity at any moment.

The fund may borrow to facilitate redemptions — principally Protocol Redeems, whose proceeds are advanced to the fund on validation. These advances are made under a drawdown credit note (the "Liquidity Facility") in which Invesco Advisers, Inc. acts as Liquidity Provider — the same entity as the Investment Manager. Key terms:

• Outstanding principal is capped at $10M.
• Interest accrues at the effective federal funds rate (the volume-weighted median per the NY Fed FR 2420 report), waivable in whole or part at the Liquidity Provider's sole discretion. Unwaived interest reduces fund returns.
• In a fund bankruptcy or default under the facility, the Liquidity Provider's claim for outstanding principal ranks senior to shareholders' rights to payment, potentially capping shareholder recovery to that extent.

For redemptions exceeding the on-chain buffer, settlement moves to the same-day Cash Needs process rather than the atomic path: the request is reviewed and funded from maturing bills and the custody cash position, within the T+2 SLA and typically same-day. The practical observation is that the binding constraint on instant (single-transaction) liquidity is the ~$10M buffer; the constraint on same-day liquidity is operational throughput and the Cash Needs windows, not portfolio liquidity, which is effectively continuous given the collateral profile. A redemption large enough to draw down the buffer faster than it can be refilled would queue to the next Cash Needs window rather than fail.

The Investment Manager retains sole discretion to suspend or postpone redemptions and payments, to introduce redemption fees, minimums, frequency limits and gates without shareholder notice, to satisfy redemptions in-kind, and to override the Continuous NAV with a "fair and equitable" determination. None of these has been exercised to date. They are the tail-risk levers an integration must underwrite: in a severe stress, on-chain atomic redemption is not a contractual guarantee.

On-chain subscriptions and redemptions are denominated in USDC; the fund also supports USD for book-entry flows. On redemption within the buffer, the holder receives USDC directly. The conversion between USD (custody) and USDC (on-chain) occurs as part of the Cash Needs replenishment cycle. Peg and convertibility risk on the USDC leg is borne while value sits in stablecoin form rather than in fund shares or in the underlying bills — a consideration for any integration that holds USDC redemption proceeds rather than immediately deploying or converting them.

The allowlist is the core compliance primitive: it is checked on every value-moving path, and both parties to any transfer must be allowlisted or the transaction reverts. It supports two mutually exclusive permission types — entity-based for KYC'd investors and protocol-based for audited DeFi contracts (which must have non-zero code size) — scoped per fund. Only the Superstate Admin Address can modify the registry. The practical implication for a DeFi integration is that the integrating protocol's contract must itself be allowlisted before USTB can move into or out of it.

The token and allowlist are upgradeable via the proxy pattern under admin authority. Key control runs through Turnkey, an institutional HSM-based key-management and signing infrastructure. Per Superstate: routine on-chain actions are signed programmatically with no humans in the loop; contract upgrades and admin actions require an M-of-N threshold (with M > 1) executed by a small set of geographically distributed signers (the specific threshold is not publicly disclosed). On-chain operations remain under Superstate's control, not the Investment Manager's — Invesco does not contribute to any on-chain operations.

Upgradeability is a residual technical risk: the admin can, in principle, change token logic. The mitigants are the M-of-N signer threshold, two-step ownership transfer, and the segregation of on-chain control (Superstate) from portfolio management (Invesco). There is no public on-chain timelock disclosed on admin actions.

The Continuous Price Oracle reverts on stale data beyond five days (StaleCheckpoint) and rejects checkpoints that deviate beyond a configured tolerance (maximumAcceptablePriceDelta), so a corrupted or stale NAV cannot silently enter an atomic transaction — the transaction reverts instead. The dual-feed design (Superstate Continuous Price Oracle and Chainlink feed in parallel) provides redundancy at the publication layer. The shared dependency is upstream: both feeds ultimately derive from Superstate's NAV/share calculation, which derives from NAV Consulting's calculation off BNY Mellon custody data. That upstream chain — not the on-chain plumbing — is the concentration point for valuation integrity.

Superstate's contracts have undergone an extensive, multi-round independent security-review process. The most recent engagement was Zellic, conducted 9–17 February 2026, scoped specifically around three questions: whether the allowlist can be circumvented, whether oracles are correctly configured and return accurate prices, and whether a user could extract more value than expected. Front-end components, infrastructure, and key custody were explicitly out of scope. Results, per the Zellic audit summary: 6 total findings — 0 critical, 0 high, 0 medium, 4 low, 2 informational — with no issues of material severity. Integrators should confirm that the deployed contract versions correspond to the audited commits, and note that the audit scope covered the contract logic, not the operational key-custody or front-end layers.

There are no reported exploits, hacks, or security incidents targeting Superstate or the USTB token contract to date. Superstate does not operate a bug bounty program with pre-defined rewards, but acknowledges legitimate vulnerability disclosures after fixes are widely deployed.

The fund's operation depends on a chain of providers, each a potential single point of failure for a different function:

• Custodian (BNY Mellon) — holds the bills and cash; the integrity of the entire structure rests here. Tier-1, independent.
• NAV Calculation Agent (NAV Consulting) — strikes the daily NAV from custody data; relies on inputs without independent verification.
• Transfer Agent (Superstate Services) — operates the on-chain infrastructure, allowlist, Continuous NAV publication, and token lifecycle.
• Oracle layer (Superstate Continuous Price Oracle + Chainlink, Pyth (Solana)) — publishes price on-chain; fails safe on staleness/deviation.
• Stablecoin ramp (USDC) — the on-chain settlement asset; introduces peg/convertibility risk on the converted leg.
• Investment Manager / Liquidity Provider (Invesco) — manages the portfolio and provides the redemption facility.

On-chain key control is managed through Turnkey's HSM infrastructure: routine actions are signed programmatically; privileged actions require an M-of-N threshold (M > 1) across geographically distributed signers, with the exact threshold undisclosed. Digital assets in transit in connection with mints, redemptions, and the instant-liquidity buffer move between the on-chain contracts and the off-chain custody/conversion process during the Cash Needs windows; the buffer contract holds only the standing USDC float, with the bulk of assets in custody at BNY Mellon.

The strongest practical resilience feature is the portfolio itself: short-dated bills self-liquidate to cash in custody at maturity, independent of the manager's or the tokenization layer's continued operation, and a successor manager can be appointed on 30 days' notice. If the tokenization protocol were paused or upgraded, atomic on-chain redemption would be unavailable for the duration, and an in-flight atomic redemption would revert rather than settle in a partial or indeterminate state (the contract design is fail-safe). Off-chain, the daily Cash Needs process and the T+2 SLA provide the fallback liquidity path.