A price-change event is not a trade receipt

A streaming feed reports a price change and the screen moves. It is tempting to treat that event as proof that your order traded. It is not.

Public market data describes the environment. Your order and trade updates describe your exposure.

Know which event you are reading

A market stream can deliver book, price-change, last-trade-price, and tick-size-change events. Each has a different meaning and an asset identifier tied to the outcome.

A price-change event may show a new level or best bid and ask. It does not say that your wallet received a fill.

Keep private state separate

Use order status and trade status to reconcile your own action. A submitted order can remain open, be partially filled, be delayed, or fail while the public market keeps moving.

Do not turn the latest public price into a position balance in your journal. Record your filled quantity and the final trade state separately.

Join on the right identifiers

Save condition ID, asset ID, timestamp, and event type with the market update. Join that snapshot to your order history only after confirming that it refers to the same outcome.

Two events that arrive close together can describe different outcomes or different moments in the same book.

Use the feed for context, not confirmation

The stream is useful for seeing how the market changed while an order was pending. Confirmation still comes from the order and trade lifecycle, followed by the updated position balance.

The useful question is not whether the price moved after you clicked submit. It is whether your exact order reached a confirmed state and changed your exposure by the amount you recorded.

Further reading: Real-time data · Market details · Order lifecycle.

Explore the markets: Open Polymarket (referral link).