The universal ticker

What an instrument means

Every instrument has a YES side, and its label always names it: KC ML (the Chiefs win), KC -3.5 (the Chiefs win by more than 3.5 points), Over 44.5 (the two teams score more than 44.5 points combined). yes_means says the same in a sentence.

A spread is always stored as “subject wins by more than L”, with L above zero. So KC -3.5 and MIA +3.5 are one instrument seen from opposite sides: MIA +3.5 is its NO side. MIA -3.5 is a different instrument.

Spreads and totals count what the sport counts: points in football and basketball, runs in baseball (the run line) and goals in hockey (the puck line) and soccer. canes over 5.5 is the two teams scoring more than 5.5 goals combined.

Soccer moneylines have three outcomes, and each is its own instrument: a club to win, the other club to win, and the draw (arsenal leeds draw). So the NO side of a club’s win is the other club winning or a draw. Soccer settles on 90 minutes plus stoppage time.

push_possible is true when the result can settle at neither 0 nor 100, such as a moneyline on a game that ends tied, and tie_rule says how the venue settles a tie (half means at 50). How Arena grades a result that is neither yes nor no is on /docs/execution.

Listings and polarity

A listing is one side of one venue market that pays on the instrument. venue names the venue, and ticker is its market. The lookups list Kalshi listings only. Kalshi is Arena’s reference venue: every game and instrument starts from a Kalshi market, and a paper trade fills at Kalshi’s price unless a best-price fill takes another venue’s.

polarity 1 means holding the listing’s side pays when the instrument is YES; -1 means it pays when the instrument is NO. Do not work it out yourself, and do not assume 1: each listing gives buy_for_yes and buy_for_no, the side of its ticker to buy to hold the instrument’s YES or NO.

Query side and instrument side

arena resolve and resolve_market answer with the instrument and query_side, the side of it your words asked for. "mia +3.5" resolves to the KC -3.5 instrument with query_side no. In the CLI, the default columns show the words’ own label, buy_side, the id and query_side.

There are two ways to trade exactly what the words asked: buy buy_side on the listed ticker (arena buy <ticker> --side <buy_side>), or pass the id with the query side (arena buy <ins_id> --side <query_side>; on the MCP server, instrument_id with instrument_side set to query_side).

With an id or slug, --side in the CLI and instrument_side on the MCP server always mean the instrument’s side. Arena maps it to the ticker’s side, and quotes and receipts show both, as instrument_side and ticker_side.

Prices on other venues

arena quotes and the MCP tool get_cross_venue_quotes show one instrument’s price on Kalshi and, while Arena shows them, on Novig, Polymarket and ProphetX, where Arena has matched a market on those venues to the same instrument. ProphetX prices come from its sandbox exchange until Arena’s production access is approved, and its rows arrive in the CLI and the npm MCP server with their next release. Every price is the chance of the instrument’s YES, whichever side of the venue’s market was read.

Each price names its venue and the time it was current. A last trade has its own time (last_trade_at), and on Polymarket each outcome’s own last trade is listed (outcome_last_trades); last_trade is always the YES outcome’s own; each outcome’s print is its price and time only. Novig’s prices arrive over Novig’s live feed when Arena’s proxy is connected to it, and by polling otherwise, so a quiet market can sit unchanged for minutes; Arena shows a Novig price up to 5 minutes old, with its time, when it could not read it again sooner: in the CLI and the MCP server a row more than a minute older than the answer has stale: true and a note, so compare as_of before you compare prices. During a game Novig shows only when Novig updated its price in the last minute, and ProphetX not at all; before a game, a Novig price Novig has not updated for 5 minutes is left out as out of date, with a note. Venues are always listed Kalshi, Novig, Polymarket, ProphetX, and are not ranked by price. When a venue’s contract differs from Kalshi’s, the note says how. For example, a tied or unfinished NFL game voids a Novig moneyline, which Novig then settles at a fair price it sets, while Kalshi settles a tie at 50%. Every Novig and Polymarket match so far was made by rule, and the note says when no person has reviewed it yet.

arena gaps and the MCP tool find_price_gaps compare the same prices after each venue’s fees. A paper trade can also take Novig’s, Polymarket’s or ProphetX’s price when it passes Arena’s checks (/docs/execution). How matching, freshness, fees, gaps and best-price fills work is on /docs/methodology. Paper trades fill in Arena’s sandbox and are not sent to Kalshi, Novig or Polymarket. Arena can stop showing other venues at any time; the answer then says cross_venue: false and lists Kalshi only.

Coverage

Full-game moneylines, spreads and game totals on half-point lines, in the NFL, college football (FBS), MLB, the NHL, the NBA and the Premier League. The Champions League is set up and gets instruments once Kalshi lists its games. Team totals, halves, player props and other leagues have no instruments yet, so the resolver answers no rows for them. Spreads and totals are added closer to the game, so a game far out may list only its moneylines, and a league out of season lists none.

The resolver reads a bet as teams plus the bet: yankees run line -1.5, canes over 5.5, arsenal -1.5, arsenal leeds draw. A name two leagues share, such as rangers, spurs or hurricanes, may need the league word. A club in two competitions resolves to its next game. In soccer, an over or under with one club or a bare number needs both clubs or the word game.