Liquidity

A price nobody can trade at is not a price. Every object that names a market carries the money behind it: what traded in the last 24 hours, what is held, what a round trip costs, and a one-word grade. Lists that suggest something to act on leave thin markets out unless you ask for them.

Volume

Field	Meaning
`volume_24h_usd`	Traded in the last 24 hours, in USD.
`volume_source`	Where that figure comes from: `venue` or `trades`.
`total_volume_usd`	Traded over the market’s life, where the venue reports it.
`open_interest_usd`	Contracts currently held, at face value. Kalshi only.
`trades_24h`	Public fills Routeur recorded in the last 24 hours.

volume_24h_usd prefers the venue’s own 24-hour figure. When a venue publishes none, it falls back to the notional of the fills Routeur recorded, and volume_source says which you got:

`volume_source`	Figure
`venue`	The venue’s own 24-hour volume. Kalshi counts contracts at their $1 face value, as its own site does; Polymarket reports USDC notional.
`trades`	Price × quantity summed over the public fills recorded in the last 24 hours.

Where both venues list one outcome (an event’s twin), volumes and open interest add up and the spread is the better of the two, because that is the venue the outcome would be traded on.

Spread

Spread is the round trip: what it costs to buy a contract and sell it straight back, in dollars of the $1 it pays.

Field	Meaning
`spread_usd`	Yes ask + No ask − $1. Absent when a side has no ask.
`yes_spread_usd`	Yes ask − Yes bid, where the venue publishes a bid.
`no_spread_usd`	No ask − No bid.

Buying Yes at 55¢ and buying No at 46¢ costs

1.01 for a pair that pays

1, so the round trip is 1¢. The per-side spreads say the same thing from one ladder: on a venue that matches Yes bids against No bids, all three are usually equal.

Grades

liquidity is deep, tradeable or thin, from the fields above:

Grade	24-hour volume or open interest	Round trip
`deep`	at least $25,000 traded, or$ 250,000 held	2¢ or less
`tradeable`	at least $1,000 traded, or$ 25,000 held	5¢ or less
`thin`	anything less	any, or no quoted round trip

Both conditions must hold for a grade: a market that traded $30,000 with a 4¢ round trip is tradeable, not deep. Open interest stands in for a market that is held rather than churned: a large book with a quiet day is still somewhere size can be moved. A market with no round trip, because one side has no ask, is thin however much it traded, since nothing can be bought and sold back at a price we know. The grade is computed when a response is built, from the latest crawl’s asks. On GET /v1/markets/{venue}/{id}/book the recorded book’s own spread grades the market instead, because it is fresher than the crawl.

What is filtered by default

Lists that suggest something to look at keep only markets that are at least tradeable, and rank what is left by the money behind it. The filter is applied inside the query, so a thin market is never read only to be dropped:

Endpoint	What it lists
`GET /v1/opportunities`	Leads
`GET /v1/insights`	The overview: gaps, movers, flows and the rest
`GET /v1/insights/moves`	What is moving
`GET /v1/insights/tape`	Large fills
`GET /v1/insights/flows`	One-sided money
`GET /v1/insights/closing`	Closing soon
`GET /v1/insights/strategies` and `/{id}`	Strategy matches

Search and event listings do not filter: they show thin markets, ranked below the ones that can be traded. Three parameters change the floor wherever it applies:

Parameter	Default	Effect
`min_volume_usd`	`1000`	Only markets that traded at least this much in the last 24 hours (or, where the venue’s figure is missing, whose recorded fills total it).
`max_spread_usd`	`0.05`	Only markets whose round trip costs at most this. Requires both asks to be quoted.
`include_thin`	`false`	`true` drops both floors and shows every market.

include_thin=true resets both floors to zero; either bound can then be set again explicitly, so include_thin=true&max_spread_usd=0.10 shows everything with a round trip of 10¢ or less, whatever it traded.

# Movers with real size only: $25,000 traded and a 2¢ round trip
curl "https://api.routeur.app/v1/insights/moves?min_volume_usd=25000&max_spread_usd=0.02" \
  -H "X-API-Key: $ROUTEUR_API_KEY"

Passing min_volume_usd=0 alone keeps the 5¢ spread floor; passing include_thin=true is what removes both.

Book depth fields

Where a market’s order book is recorded (see Order books), five more fields come from the book itself, not the crawl:

Field	Meaning
`book_spread_usd`	Best Yes ask − best Yes bid.
`book_yes_depth_5c_usd`	USD resting to buy Yes within 5¢ of the best Yes bid.
`book_no_depth_5c_usd`	USD resting to buy No within 5¢ of the best No bid, which is money waiting to sell Yes.
`book_imbalance`	(Yes depth − No depth) / (Yes depth + No depth) over those 5¢ windows, from −1 (all the money is on No) to +1 (all on Yes).
`book_at`	When the recorded book last changed.

They are omitted for markets with no recorded book, and can be older than the crawl’s asks for markets in the polled tier. Compare book_at with quote.observed_at when it matters.

Example

An MLB total on Kalshi, read from GET /v1/markets/kalshi/KXMLBTOTAL-26SEP171235MILPIT-9/book (liquidity fields only):

{
  "volume_24h_usd": "16742.70",
  "volume_source": "venue",
  "total_volume_usd": "16966.44",
  "open_interest_usd": "15593.36",
  "spread_usd": "0.01",
  "yes_spread_usd": "0.01",
  "no_spread_usd": "0.01",
  "trades_24h": 94,
  "liquidity": "tradeable",
  "book_spread_usd": "0.01",
  "book_yes_depth_5c_usd": "56704.17",
  "book_no_depth_5c_usd": "72750.02",
  "book_imbalance": "-0.124",
  "book_at": "2026-09-17T12:42:01.052454Z"
}

16,743 traded and a 1¢ round trip: tradeable, not deep, because it is short of the

25,000 the top grade needs.

57,000 rests within 5¢ on the Yes side and

73,000 on the No side, so the book leans slightly toward sellers of Yes.

Order books: where the book_* fields come from.
Leads: why only tradeable markets become opportunities, and how depth sizes them.
Quotes and trades: the asks and fills the figures are read from.
Data freshness: how old each figure can be.

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Reference

Volume

Spread

Grades

What is filtered by default

Book depth fields

Example

​Volume

​Spread

​Grades

​What is filtered by default

​Book depth fields

​Example

​Related

Volume

Spread

Grades

What is filtered by default

Book depth fields

Example

Related