Arcus and Ostium both quote 20 of the same perpetual markets, so a delta-neutral position can be split across the two and collect the difference in their funding. The widest spread on a market with real depth is CRWV — long Ostium / short Arcus at 66.5% net APR — but the median across all shared markets is 22.4%, which is the number worth planning around.

The long leg is whichever venue prices funding lower for that market. It is a property of the MARKET, not of the exchange, and it flips as rates move: here 4 markets go long on Arcus and 16 on Ostium. 17 markets clear 5% net APR, 14 clear 10%.

Arcus pays funding every 1h on 63 markets; Ostium pays every 1h on 53 markets. Both sides settle on the same clock, so a position opened here collects or pays on both legs at once — the spread you see is the spread you get. Arcus quotes 63 perpetual markets in total and Ostium quotes 53; the 20 they share are what this page ranks. Across its own book Arcus runs a median funding rate of 10.9% and Ostium 0.0% — the two sit on opposite sides of zero, which is why this combination throws up spreads at all.

Net APR subtracts entry and exit fees, both legs' bid/ask spread and estimated slippage from the gross funding spread. The 7-day average is historical gross funding for the same pair: a current rate close to it suggests the spread has persisted, one far above it is usually a spike that will decay.