Base, the Coinbase-backed Ethereum Layer-2 network, activated its Cobalt hard fork on mainnet on September 30, 2026. The upgrade, which went live at approximately 18:00 UTC following a maintenance window, introduces conditional transaction execution and new administrative features for the network’s native B20 token standard.

Cobalt marks Base’s third major network upgrade. It follows successful deployment on the Base Sepolia testnet on September 23. Node operators were required to run software version 1.4.2 or later ahead of the mainnet activation.

Validity Transactions Enable Condition-Based Execution

A core addition is Validity Transactions. These allow users to submit signed transactions that remain ineligible for inclusion until specified on-chain conditions are satisfied. Supported conditions include balance thresholds, storage values, block numbers and Flashblock-index predicates.

The mechanism works with legacy, EIP-2930 and EIP-1559 transaction types. An example use case involves a trader submitting a swap that becomes eligible only if an asset reaches a target price before a designated block deadline. Base evaluates the conditions against chain state as blocks are produced. Transactions submitted this way can remain private until they enter a block.

This design aims to support more precise timing for conditional strategies while limiting premature visibility of intent.

Expanded B20 Standard for Compliance and Corporate Actions

Cobalt significantly extends the B20 token standard, which Base activated on July 8 as a native framework for fungible tokens including stablecoins and tokenized real-world assets. Issuers can now attach multiple compliance requirements to a single asset under unified policies.

Composite policies using Union and Intersect logic let issuers combine checks such as identity verification, qualified-investor status and sanctions screening. The upgrade also simplifies transfer-blocking functionality and adds scheduled multiplier updates.

For corporate actions such as stock splits, issuers can preset adjustments that alter the share quantity displayed in wallets and applications. These changes occur without minting or burning tokens and without modifying the underlying balance held by users.

Issuers may authorize administrators to transfer tokens from a holder’s address without the holder’s approval. Any such transfer must include a public on-chain explanation. Base itself cannot initiate these movements; the feature remains under issuer control and is optional.

Infrastructure Changes for Upgrades and Signers

Beyond token and transaction features, Cobalt introduces an automated process for future network upgrades. An Ethereum smart contract stores fork timestamps so Base nodes can read the schedule and activate changes at the designated time without requiring a client restart. On mainnet the system is currently operating in metrics-only mode.

The upgrade also revises registration for Trusted Execution Environment signers. AWS Nitro attestations are now verified fully on-chain using checked P-384 hints, replacing the previous proving flow that relied on external services.

Context Within Base’s Tokenized Finance Push

The Cobalt activation continues Base’s recent focus on on-chain finance. In July, network creator Jesse Pollak stated that Base had prioritized creator and messaging applications at the expense of financial use cases such as prediction markets and perpetual futures, and that trading and payments would receive greater attention going forward.

On August 25, Coinbase launched tokenized U.S. stocks on Base as B20 tokens representing shares in companies including Apple, Nvidia, Meta and Alphabet. The new compliance and administrative tools in Cobalt are intended to support the requirements of such regulated or permissioned assets.

Looking ahead, Base has outlined plans to reduce block times from two seconds to 200 milliseconds, add protocol-level support for sponsored fees and bundled transactions, and incorporate selected changes from Ethereum’s upcoming Glamsterdam upgrade.

No major incidents were reported during the mainnet activation window.