What is a spread in arbitrage
The price difference for the same asset between two markets, in percent. The two markets can be two exchanges, or spot and a perpetual on one exchange.
In the product
The market monitor in Z Market Lab shows an Open spread and a Close spread for each opportunity. Both use the best bid and ask you can fill immediately, with the long leg’s price as the denominator. A ZML Trade combo opens and closes on the spread: it opens at the Open trigger and closes at the Close trigger.
How to read it
A positive Open spread means the price you can sell at on the short leg is above the price you can buy at on the long leg. The Funding diff is the difference between the funding rate of two markets, a separate measure. See What is a cross-exchange spread and Round-trip spread.