Spark Opens Its USDT Savings Vault To OKX Users

Spark, an on-chain capital allocation platform that originated as a subDAO of Sky (fka MakerDAO, is opening its USDT savings vault to OKX customers, letting users of the centralized exchange earn onchain yield on their stablecoin balances from inside the OKX app, according to a statement shared with The Defiant ahead of publication.

The arrangement moves exchange-held stablecoins into an onchain vault without the customer opening a wallet or bridging funds. OKX aggregates customer deposits and routes them into Spark Savings USDT on X Layer, OKX's Ethereum Layer 2, rather than having each user hold the vault token directly. Deposits sit in the same vault contract available to any X Layer user, Spark told The Defiant, not in a segregated OKX pool.

The vault pays 3.5%, according to the savings rate stored in the vault contract on X Layer, the same rate set on Spark's Ethereum USDT vault. Aave's Ethereum USDT market paid a base supply rate of 3.72% on Thursday, per DefiLlama. Spark declined to give a rate before launch, citing legal restrictions.

Cap On An Empty Vault

Spark's USDT deposits sit almost entirely on Ethereum, where the vault held $359.9 million. Spark put the USDT savings total at approximately $361 million in written answers to The Defiant.

Spark governance set the X Layer vault's supply cap at 750 million USDT and its maximum yield at 6%, according to the parameters added to the Spark Artifact in July. X Layer secures $130.4 million in total, per L2BEAT, so the cap is close to six times the value on the chain today.

Spark targets a liquidity buffer on X Layer of the greater of 10% of deposits or $1 million, capped at $10 million, with the rest bridged back to Ethereum for deployment. Instant withdrawals draw on that buffer.

Deposits Arrive As USDT0

The deposit asset on X Layer is USDT0, the LayerZero-issued omnichain version of Tether's dollar token, per Spark's documentation. Native USDT is the deposit asset only on Ethereum.

Spark's Liquidity Layer moves the pooled capital across approved venues including SparkLend, Morpho vaults and real-world asset strategies. Spark added institutional lending products earlier this year and seeded a stablecoin trading layer on Uniswap v4 with $150 million. For every dollar deposited into Spark Savings, Spark borrows an equivalent amount of USDS through Sky's allocation system, giving the vault 1:1 USDS backing.

"OKX provides the familiar exchange experience, X Layer provides the on-chain environment connecting that experience to DeFi, and Spark provides the allocation intelligence that coordinates capital across approved lending, liquidity and credit opportunities," Sam MacPherson, co-founder and chief executive of Spark, said in the release.

Jason Lau, OKX's chief innovation officer, said routing the product through X Layer "means eligible USDT holders can access a meaningfully differentiated savings product without any of the traditional DeFi onboarding overhead."

Who Absorbs A Loss

Spark said savings deposits rank alongside USDS holders in the Sky ecosystem's loss hierarchy. Losses hit Spark's junior risk capital first, then Sky's surplus buffer, then excess capital held across Sky entities, then newly issued SKY tokens. If those layers are exhausted, remaining deficits are socialized across USDS holders, and Sky can set the USDS target price below $1, according to Spark's security framework.

Spark's own risk reviewers flagged the chain the deposits land on. X Layer lacks a sufficiently decentralized proof system, so "security of the funds relies heavily on the operator which can also instantly upgrade the chain," the Spark Risk Council wrote in July when it cleared the deployment for a vote. L2BEAT places the chain in its "others" category for the same reason. The council capped exposure with a $5 million maximum transaction size on outbound flows from Ethereum and noted that a compromised relayer could set the vault yield no higher than 6%. BA Labs, the Core Council and Sky's risk function set the X Layer buffer at a 100% capital requirement ratio until the chain could be reviewed.

Approved In July, Announced Now

Phoenix Labs proposed spUSDT on X Layer on July 6 alongside USDT bridging rate limits from Ethereum, and both went to a joint Snapshot poll for the July 16 spell. The vault was live by July 20, when governance moved to record its onchain parameters. Spark governance requires approval for new chain deployments and protocol integrations, per its documentation. No proposal names OKX as a distribution partner.

Spark Savings USDT will be available to eligible OKX users outside the European Union, according to the release. In answers to The Defiant, Spark's representatives said the product is available globally excluding European Economic Area countries and other jurisdictions OKX restricts.

Spark holds $6.47 billion in total value locked, per DefiLlama, across Ethereum, Base, Arbitrum, Robinhood Chain and Gnosis. Its SPK token traded at $0.0189 Thursday, down 4% on the day and up 34.3% over 30 days, per CoinGecko, for a market value of about $62 million.

The two companies said further integrations are under consideration.