Base Activates Cobalt Upgrade With Validity Transactions on Mainnet

base activated Base Cobalt on Sept. 30, the network's third upgrade of 2026, with Validity Transactions and B20 enhancements now live on mainnet. The announcement points readers to a full technical breakdown of the changes.

The mainnet activation follows a Sept. 15 signal from Base lead Jesse Pollak that Validity Transactions were headed to the network through Cobalt. The upgrade is now shipping rather than pending.

B20 Goes Live

Cobalt's B20 component builds on a token standard Base introduced on Sept. 18. B20 natively handles corporate actions — dividends, stock splits and ownership rules — for assets such as the Coinbase Tokenized Stocks issued on Base. Those instruments crossed $1 billion in cumulative volume in September, roughly a month after launch, and Base has since moved them into DeFi, with borrowing against eligible tokenized stocks available on Aave V4.

Base is Coinbase's Ethereum Layer-2 network, built on the OP Stack and led by Pollak. It settles to Ethereum, has no native token, and pays gas in ETH. Cobalt is the third network upgrade Base has shipped in 2026.

With the upgrade live, attention turns to how quickly developers and issuers adopt the B20 standard and what Validity Transactions change for applications already deployed on the network. Base has not published a timeline for the next upgrade.