By Maya Rowan · Fictional AI writer for The Closing Line
A Kalshi price alert starts with a question: do you want to know about a completed trade, an offer to sell YES, or an offer to buy YES? Those are different signals. Choosing a threshold before choosing the signal can give you an alert that answers the wrong question.
The Closing Line’s price alerts page offers last-trade and YES bid/ask monitoring. This guide explains how to choose between them, using an invented market snapshot rather than a trading recommendation.
What last trade, bid, and ask tell you
Last trade refers to a completed transaction. For this article, prices are expressed on the YES side. A trade at 46¢ records a transaction at that price; it does not establish that someone is still offering YES at 46¢. Kalshi’s trade records include a price, quantity, and timestamp, which help distinguish the transaction from a current quote. Kalshi trade documentation
YES bid is the highest current price offered by a buyer of YES. YES ask is the lowest current asking price for YES. The order book shows resting orders and their quantities. A quote therefore describes an offer, while a trade describes an exchange that already happened. Kalshi order-book explanation
Use this small decision table before entering a number:
| Question you want the alert to answer | Price to watch |
|---|---|
| Has a completed YES trade reached my threshold? | Last trade |
| Has the displayed asking price for YES fallen to my threshold? | YES ask |
| Has the displayed bid for YES risen to my threshold? | YES bid |
These are examples of monitoring questions. None says whether the contract is correctly priced or whether you should trade it.
A worked example: 46¢ last, 41¢ bid, 44¢ ask
Synthetic example: imagine a market with a last YES trade of 46¢, a best YES bid of 41¢, and a best YES ask of 44¢. These numbers are invented. They are not live market data, a backtest, or a record of an alert being delivered.
Suppose you are comparing three possible alert rules:
| Rule | Comparison at this snapshot | Condition met? |
|---|---|---|
| Last trade ≤ 42¢ | 46 ≤ 42 | No |
| YES ask ≤ 42¢ | 44 ≤ 42 | No |
| YES bid ≥ 47¢ | 41 ≥ 47 | No |
Now consider three separate updates, each starting from that same snapshot:
- A new YES trade occurs at 42¢; the bid and ask remain 41¢ and 44¢. The last-trade condition is met. The ask condition is not: the displayed ask is still 44¢.
- The YES ask falls to 42¢; the bid stays 41¢ and no new trade occurs. The ask condition is met. The last-trade condition is not: its observed trade price remains 46¢.
- The YES bid rises to 47¢ and the ask moves to 49¢; the last trade remains 46¢. The bid condition is met. Neither of the other conditions is met.
“At or below” includes the threshold itself: 42¢ meets ≤ 42¢. Likewise, 47¢ meets ≥ 47¢. The table demonstrates the comparisons, not whether or when a production notification will arrive.
This is why an alert described only as “tell me when the price hits 42” is incomplete. Writing “tell me when the YES ask is at or below 42¢” identifies the observation you actually want.
Keep YES and NO prices straight
The labels in this example are all YES prices. If you are reading a NO quote elsewhere, do not copy its number into a YES alert without translating the side.
For a standard binary contract, Kalshi documents the complementary relationship: the best YES ask is $1 minus the best NO bid. A 56¢ NO bid therefore corresponds to a 44¢ YES ask. Similarly, the best NO ask is $1 minus the best YES bid. These are relationships between opposite sides of the book; they do not turn a quote into a completed trade. Kalshi order-book response documentation
What to check after a notification
An alert is a prompt to inspect the market. Read the current quote and the quantity available at that price instead of treating the notification’s number as a fill confirmation. Kalshi’s order-book display includes both price and quantity. Kalshi order-book explanation
An order is a separate decision. Even a limit order may remain unfilled, so a price condition being met is not evidence that your order executed. Kalshi limit-order explanation
A short alert worksheet
Before saving an alert, fill in these five lines:
- Market: the exact market and outcome I intend to monitor.
- Observed price: last trade, YES ask, or YES bid.
- Condition: at or below ___¢, or at or above ___¢.
- Reason to look: the question I want to investigate when notified.
- Next check: current bid, ask, quantity, and the age of the displayed trade.
Read the sentence back in plain language. If your question is about an asking price but your sentence says “last trade,” revise the field before saving.
Open The Closing Line alerts to review the available controls. For the notification setup steps, see the Kalshi price-alert setup guide.
About the author: Maya Rowan is a fictional AI editorial persona created by The Closing Line. The name represents a consistent guide-writing and product-education voice, not a real person or independent financial professional. The Closing Line is responsible for this content and its corrections. Questions or corrections. Meet our writers.