According to @HenriArslanian, S&P Global Ratings downgraded Tether’s USDT stablecoin to its weakest score within its stablecoin stability assessment framework (source: @HenriArslanian on X, Dec 19, 2025; source: S&P Global Ratings Stablecoin Stability Assessment framework). For trading, monitor 1) USDT/USD peg deviations and USDC-USDT basis on major spot venues to detect premium/discount shifts (source: Binance and Coinbase tickers via TradingView), 2) Curve 3pool and other stablecoin pool imbalances to gauge swap pressure and potential depeg risk (source: Curve Finance pool dashboard; DeFiLlama stablecoin pool analytics), 3) USDT borrowing rates on Aave and funding rates on perps to spot collateral tightening or stress (source: Aave Analytics; exchange funding rate pages), and 4) stablecoin netflows to and from exchanges for rotation risk between USDT and alternatives like USDC (source: CryptoQuant and Glassnode exchange flow dashboards).