Aave lowered the optimal utilization threshold for USDT on its Ethereum Core market from 94% to 92% on October 21, moving the steeper portion of the borrowing rate curve earlier and raising borrowing costs as pool liquidity tightens.
The change, executed in Ethereum block 26,241,799, alters how the protocol’s two-slope interest rate model prices USDT loans. Under the new structure, borrowing APR jumps to 7% at 94% utilization, compared to 4.5% under the prior curve. At full utilization (100%), the borrowing rate remains at 14.5%.
LlamaRisk, a DeFi risk service provider, had issued a recommendation on October 20 when 2,892.2 million USDT was supplied to the market. The risk firm flagged 417 million USDT sitting idle in the pool and modeled that lowering the utilization threshold would create an additional 57.8 million USDT buffer without requiring new physical capital.
Rate Mechanics Under the New Threshold
Aave’s interest rate model applies a base rate of 0%, a first slope of 4.5% up to the optimal utilization point, and a second slope of 10% beyond it. By moving the kink from 94% to 92%, borrowers face steeper rate increases sooner as the pool approaches capacity.
On a 1 million USDT loan, the 2.5 percentage point rate gap between the old and new curves at 94% utilization translates to approximately 25,000 USDT in additional simple annual interest.
The change creates modeled headroom in the pool’s accounting, but actual cash availability depends on user behavior. At the October 23 snapshot (block 26,254,517, timestamped 09:45:59 UTC), unborrowed liquidity stood at 231.38 million USDT under the new 92% threshold, compared to 173.53 million USDT at the prior 94% level. However, physical USDT held at the aToken contract was only 391.4 million, substantially lower than the 2.9 billion USDT in outstanding supplier claims.
Pool State at October 23
Borrow utilization reached 86.45% by the October 23 snapshot. Variable debt totaled 2.5 billion USDT against 2.9 billion USDT in supplier claims. The variable borrowing APR was 4.23%, while suppliers earned 3.29% on their liquidity. The protocol’s reserve factor, set at 10%, directs a portion of borrowing interest to the Aave treasury.
Suppliers can withdraw only against unborrowed liquidity; accrued interest does not guarantee immediate withdrawal availability. The gap between virtual accounting balances and physical cash underscores the importance of the utilization threshold in managing withdrawal pressure as the pool tightens.
CryptoSlate, through reporting by Liam Wright and Gino Matos, documented the parameter change and its effects on the USDT market structure.
