Arbitrage normally ensures that covered interest parity holds. Yet, this paper shows that this central condition in finance broke down for several months after the Lehman bankruptcy for trades funded in dollars. This anomaly emerges for two popular arbitrage strategies, using both unsecured and secured funding. The secured strategy, newly investigated in this paper, avoids default and rollover risks, thus favoring funding liquidity constraints as an explanation for arbitrage deviations. Additional empirical tests support this hypothesis, although also point to contract risk. Moreover, official policies to alleviate funding liquidity strains, such as foreign exchange swaps, contributed to restoring arbitrage.JEL classification: F31, G01, G14