Unusual activity and z-scores

Some contracts always trade a lot and some almost never do, so a raw volume ranking mostly lists the busy ones. Unusual activity asks a better question: is this contract trading much more than its own normal?

For each contract Knowla keeps its volume on previous days, one sample per trading day. The z-score is how many standard deviations today's volume sits above that contract's own average. A z-score of 3 or more is rare for a contract in a steady state, so it is listed. A spread floor stops a contract with almost no history from reading as infinitely unusual.

A z-score needs at least five prior days. Until a contract has them, the page falls back to a simpler test: it lists the contract if it traded more than twice its open interest, and it says which test applied to each row. Either way only contracts trading at least about $100,000 are considered, so tiny prints do not crowd the list.

This is not insider news, and it does not say who traded or in which direction. A busy contract can be a hedge, an expiry roll, a market maker adjusting, or a single large trader. Treat a flag as a reason to look at the contract, then at its open interest and the days around it.