YES = USDT < $0.98 for 7 days.

Will use price data from one of the top exchanges at the time (e.g. today in 2023 I would use Coinbase).

Background: USDT is a stablecoin managed by Tether (company). There have been rumors for a long time that Tether may not have enough assets to fully back the USDT stablecoins distributed in the crypto-economy (~$80B). If it were found that tether insolvent, or something else happened to shake confidence in USDT's redeemability to USD, then the price could depeg.

I picked 1 week so it would indicate a serious issue, i.e. probably irredeemable reputational damage and likely leading to users abandoning the stablecoin. For reference the 2023 USDC depeg didn't stay below 98c for more than a day, even though it did go down much more; the issue was resolved in days.