In a BIS working paper, Dagfinn Rime, Andreas Schrimpf, and Olav Syrstad analyze the apparent breakdown of covered interest parity (CIP). They argue that
CIP holds remarkably well for most potential arbitrageurs when applying their marginal funding rates. With severe funding liquidity differences, however, it becomes impossible for dealers to quote prices such that CIP holds across the full rate spectrum. A narrow set of global top-tier banks enjoys risk-less arbitrage opportunities as dealers set quotes to avert order flow imbalances.