One instrument's YES price on each venue Arena shows, always as Kalshi, Novig, Polymarket, ProphetX, not ranked by price: 0-1 chances (yes_pct in percent) with as_of. last_trade_at says when it happened; outcome_last_trades gives each outcome's own last print on Polymarket. Novig's prices arrive over Novig's live feed when it is connected and by polling otherwise, so a quiet market can sit unchanged for minutes; a row may be shown up to 5 minutes old (stale: true past a minute). ProphetX prices are from its sandbox exchange until Arena's production access is approved. When cross_venue is false only Kalshi is listed. Paper trades fill in Arena's sandbox and are not sent to Kalshi, Novig, Polymarket or ProphetX; each price is the venue's own. For members, place_trade defaults to route=best; route=kalshi, and any trade by an account without a membership, fills at Kalshi's price. No sign-in.