NexusBTC (NBTC)

This review rejects NexusBTC because one entity controls it, no redemption path is disclosed, and its issuer’s unresolved corporate wind-down adds further risk. NexusBTC is a wrapped Bitcoin token issued in connection with bit.com, whose parent Matrixport began winding down the exchange in December 2025 and rebranded its combined platform as BIT in March 2026. A direct on-chain query confirms that the token contract sits behind an EIP-1967 upgradeable proxy, the same single-entity-controlled design already rejected in this registry for Binance-Peg BTCB. This review found no NexusBTC-specific reserve attestation, redemption process, or timing anywhere, even though BIT’s custody arm has real institutional credentials.

Review triggers: events that reopen the 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

Watched nightly: a warning on its venues or files, or a cited document that changes, reopens the memo. The first confirmation is due 2026-11-18.

The research file

Mechanism

NexusBTC says a Bitcoin reserve backs it at or above a 1:1 ratio and that the token supports cross-chain transactions. A direct eth_call against the Ethereum contract confirms the token name and a total supply on the same scale as its tracked TVL. This review found no disclosed mint or redeem process, custody address, or reserve report in any source it reached.

Control and governance

A direct on-chain read of the contract’s EIP-1967 implementation storage slot confirms that this is an upgradeable proxy with a non-zero implementation address. A single controlling entity can therefore change the token’s logic at will. This is the same design already found for Binance-Peg BTCB, which this registry rejected. The specific admin or upgrade-authority address could not be confirmed. DefiLlama’s own description ties the token to bit.com, which shut down as a separate exchange in March 2026 after a wind-down that began on 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 and has a proof-of-reserve partnership. But this review found no NexusBTC-specific reserve attestation, audit, or custody disclosure anywhere in this pass.

Incident record

This review found no confirmed exploit, depeg, or hack involving NexusBTC, bit.com, Matrixport, or BIT through its 2026-08-18 search cutoff. Press coverage describes the bit.com shutdown as a business restructuring decision, not a security incident. Still, the shutdown directly affects the question of whether this token remains a live product with active minting and redemption.

Exit

This review found no disclosed redemption process, timing, or gating condition anywhere for NexusBTC. The parent exchange’s own wind-down makes that gap worse. This review could not confirm whether NexusBTC minting and redemption remain active at all after the bit.com-to-BIT transition.

Comparison

NexusBTC has weaker disclosures than Kraken Bitcoin or Lombard BTC.b, both approved with limits in this registry for regulated or multi-party custody with public redemption terms. It shares the rejected upgradeable-single-entity-proxy design of Binance-Peg BTCB, but adds an unresolved question about corporate continuity that BTCB does not carry: whether the issuing brand still operates in any form that would honor a redemption request. That leaves NexusBTC in a weaker position even than related entries in this same wind-down category. Unlike a WBTC or BTCB holder, a NexusBTC holder cannot point to any surviving operating team 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 research above describes the protocol layer. Every position also inherits the asset it holds and the chain it settles on. The layer with the most administrative power sets the position’s effective control; that describes control, not quality or suitability.