NexusBTC (NBTC)

Rejected venues wait the longest for re-review; a rejection has to earn another look before the scheduled date.

REJECTED ON CONFIRMED SINGLE-ENTITY CONTROL AND NO DISCLOSED REDEMPTION PATH, COMPOUNDED BY AN UNRESOLVED CORPORATE WIND-DOWN. NexusBTC is a wrapped Bitcoin token issued in connection with bit.com, whose parent Matrixport wound the exchange down starting December 2025 and rebranded its consolidated platform as BIT in March 2026. A direct on-chain query confirms the token contract sits behind an EIP-1967 upgradeable proxy — the same single-entity-controlled architecture already rejected in this registry for Binance-Peg BTCB — and no NexusBTC-specific reserve attestation, redemption mechanism, or timing was found anywhere in this review, despite BIT’s custody arm otherwise carrying real institutional credentials.

Kill criteria: the events that revoke this verdict
• BIT or Matrixport publishes an independent, NexusBTC-specific proof-of-reserve attestation
• A disclosed, permissionless or clearly documented redemption path for NBTC is published and demonstrated
• The proxy admin or upgrade-authority address is publicly disclosed and confirmed to sit behind a multisig rather than a single key
• NexusBTC’s active operational status following the bit.com wind-down is confirmed directly by BIT or Matrixport

The research file

Mechanism

NexusBTC markets itself as backed at or above a 1:1 ratio by a Bitcoin reserve, facilitating cross-chain transactions. A direct eth_call against the Ethereum contract confirms the token name and a total supply consistent in scale with its tracked TVL. No disclosed mint or redeem process, custody address, or reserve report was found in any source reached in this review.

Control and governance

A direct on-chain read of the contract’s EIP-1967 implementation storage slot confirms this is an upgradeable proxy with a non-zero implementation address, meaning a single controlling entity can change the token’s logic at will — the same architecture pattern already found for Binance-Peg BTCB, rejected in this registry. The specific admin or upgrade-authority address could not be confirmed. bit.com, the entity DefiLlama’s own description ties this token to, shut down as a distinct exchange in March 2026 following a wind-down beginning 2025-12-27; its parent, Matrixport, rebranded its platform as BIT on 2026-03-20. BIT’s custody arm, Cactus Custody, is SOC 2 Type II certified and Deloitte-audited with a proof-of-reserve partnership, but no NexusBTC-specific reserve attestation, audit, or custody disclosure was found anywhere in this pass.

Incident record

No confirmed exploit, depeg, or hack was found for NexusBTC or for bit.com, Matrixport, or BIT through this review’s 2026-08-18 search cutoff. The bit.com shutdown itself is characterized in press coverage as a business restructuring decision, not a security incident, but it directly bears on whether this token is still an operationally live, actively minted and redeemed product.

Exit

No redemption mechanism, timing, or gating condition was found disclosed anywhere for NexusBTC. That gap is compounded, not merely sitting alongside, the parent exchange’s own wind-down: this review could not confirm whether NexusBTC minting and redemption remain operationally active at all following the bit.com-to-BIT transition.

Comparison

Weaker-disclosed than Kraken Bitcoin or Lombard BTC.b, both approved with limits in this registry for regulated or multi-party custody with public redemption terms, and shares Binance-Peg BTCB’s rejected upgradeable-single-entity-proxy architecture, but with an added, unresolved corporate-continuity question BTCB does not carry: whether the issuing brand still operates in any form that would honor a redemption request. That leaves NexusBTC weaker-positioned even than sibling entries in this same wind-down category: a holder cannot point to any surviving operational team the way a WBTC or BTCB holder could in a dispute.

Sources

The claims above trace to these. Where a number could not be independently verified, the thesis says so.

• DefiLlama — Nexus BTC protocol record · secondary · accessed 2026-08-18
  Supports: identity, description, category
• Ethereum mainnet, direct on-chain query: NexusBTC contract name, supply, and EIP-1967 proxy check · primary · accessed 2026-08-18
  Supports: upgradeable-proxy confirmation, total supply
• BIT (formerly Matrixport) — official site · primary · accessed 2026-08-18
  Supports: bit.com to BIT rebrand, Cactus Custody credentials
• CoinCodeCap — Matrixport review: bit.com closed 2026, platform still active · secondary · accessed 2026-08-18
  Supports: wind-down timeline, rebrand date
• Crypto.news — Cactus Custody passes Deloitte security audit · secondary · accessed 2026-08-18
  Supports: custody-arm credentials, not NexusBTC-specific

Inherited controls

The verdict above grades the protocol layer. Every position also inherits the asset it holds and the chain it settles on. The least safe layer sets the position’s grade, and the position table names which one that is.