Markets, events and series

How Series, Events and Markets relate — and which mechanism a market uses.

XO groups related questions without changing what you actually trade.

Level	What it is
Series	An optional collection of related events.
Event	The topic page and rules context. An event can contain markets directly, or use one level of sub-events before the market lines.
Market	One tradable condition, with its own outcome tokens and its own settlement rules.

The market is the unit that settles. Two market lines under the same event are separate conditions — separate rules, separate books, separate outcomes — even when they share a topic page.

Two trading mechanisms

XO currently exposes both an order book and a legacy automated market maker. Which one you get depends on the market.

	Order book (CLOB)	Legacy AMM
Counterparty	Other traders’ resting orders	A pricing pool
Route	/event/[slug]	/markets/[slug]
Limit orders	Yes	No
Visible depth	Yes	No
Quote shows	Book depth, average price, protection price	Price impact and slippage

Market cards label the mechanism. Check it before opening a market — the controls available to you differ. See Place an order and Legacy AMM markets.

Market states

State	What it means for you
Active	Trading is open.
Paused	New orders are rejected. Existing resting orders are retained and the market can return to Active.
Resolved	Terminal. An outcome was recorded; resting orders are cancelled; winning positions can become claimable.
Voided	Terminal. The market was invalidated under its published rules; eligible positions follow the defined refund path.
Closed	Terminal. The market ended without a resolution under engine rules.

Integrators can read the same lifecycle from the API side in Market lifecycle.