Price War or a Market-Wide Signal: How to Read the Sequence of Changes

Two sellers cut their prices. Is this already a price war — or did the market just receive a shared signal?

Drawing conclusions from a single price drop is premature. Even a sequence of changes doesn't reveal the sellers' intentions and doesn't by itself prove why they reacted. To analyze it, you need to reconstruct the timeline: who changed the price first, when the subsequent changes appeared, what was happening with availability, and how comparable the timestamps are.

Demo scenario

Listing A changes its price. Some time later, changes appear on listings B and C. At first glance this may look like the participants reacting to one another. But the same sequence of events can arise from a change in marketplace conditions, a discount, a promotion, a data update delay, or sellers' independent decisions.

So the first price drop is a signal to investigate, not a ready-made conclusion about a price war.

What to record in the timeline

For each listing, store:

• the listing ID or SKU;
• the original and new price;
• the time the change was recorded;
• the data source;
• the availability status;
• the time the availability information was updated;
• a note about any possible update delay.

Then check:

1. Which listing changed first?
2. After what interval did the subsequent changes appear?
3. Did several sellers change their prices, or only one?
4. Did the product remain available?
5. Did the price changes coincide with availability changes?
6. Can the timestamps be considered comparable?

Price, availability, and time are related but not interchangeable signals. A listing disappearing doesn't mean the seller cut the price. A price change while the product is out of stock doesn't necessarily reflect competitive struggle. Close timestamps don't prove simultaneous action either: data sources may update with a delay.

What marketplace data shows

The Yandex Market API documentation describes a listing's price and the time of its last update via the `updatedAt` field. Stock data may include the available quantity and the time of the last update. These fields help compare observable events, but they don't explain the seller's motive.

The Wildberries documentation describes methods for retrieving prices and checking seller stock levels. At the same time, the statistics service doesn't store stock history: it only gives access to the current state. If you need to analyze past product availability, you should record it in advance with your own monitoring system.

There are freshness limitations to the data. The Wildberries documentation states that stock reports are updated once an hour, and data synchronization with the services can take up to 30 minutes. Therefore, the proximity of timestamps cannot automatically be interpreted as synchronous action by sellers.

How to separate fact from hypothesis

**Confirmed fact:** a listing changed its price at a recorded moment.

**Confirmed fact:** later, a similar change appeared on another listing.

**Confirmed fact:** the availability of one or more listings changed or remained available.

**Hypothesis:** the second seller reacted to the first.

**Hypothesis:** several sellers received a shared market signal.

**Unknown circumstance:** whether the change is related to marketplace conditions, a discount, a promotion, a data delay, or an independent seller decision.

This distinction helps prevent you from automatically cutting your own price just because a cheaper card appeared next to you.

Practical algorithm

Build a timeline across several listings and record price, availability, and time separately. Check whether the scenario repeats, whether the product stays available, and how reliable the timestamps are. Then split the result into three groups:

1. what the system actually recorded;
2. which explanations can be tested further;
3. what the current data cannot establish.

Only after that should you decide how to respond with your own price.

A repeating sequence may be an important market signal, but it's more accurate to talk about confirmed observable changes rather than proven seller intent. Price and availability show what happened to a listing. They don't show why it happened.

Build a timeline of changes across several listings and separately note the confirmed facts and the unknown circumstances. Don't conclude that there's a price war based on a single drop or a coincidence in time.