Cross-exchange funding-rate arbitrage

A common setup goes long on the lower standardized rate and short on the higher standardized rate, with notionals matched as closely as contract specifications allow.

Equal notionals reduce directional exposure but do not eliminate it. Mark prices, contract multipliers, basis, fill timing, and collateral differ across venues, so the two legs can diverge during a fast market.

Compare the same holding window, allowing for changing funding, notionals, and settlement eligibility. A normalized spread is not locked income.

A positive-rate perpetual long pays funding and may reduce receipts compared with an available spot hedge. A negative-rate long can add receipts but introduces another margin and liquidation system. The spot holding need not use the same exchange as the short.

Opening and closing both legs creates four executions. If each execution is modeled at 0.04% in fees plus 0.02% in slippage, the simplified round-trip cost is 0.24% before basis and funding-transfer effects.

At a gross 0.020% per eight hours, roughly twelve similar windows would be needed just to cover that simplified cost. The current spread is therefore a screening input, not an executable return.

Different mark-price rules, contract multipliers, liquidation systems, and settlement times can make equal notionals drift apart.

Exchange failure, withdrawal suspension, margin imbalance, and a rapid funding reversal can turn a nominal arbitrage into a loss.