Once your scenario has run, the Metrics & risk panel rates every local market as high, medium or low risk, using the concentration metrics and thresholds you choose. Use it to focus on the markets most likely to raise concerns, and to test how sensitive your results are to different thresholds.

Where to find it

On the Scenarios page, the Metrics & risk panel sits to the right of the All local markets map. Use the icon at its top right to collapse or expand it.

Step 1 - Choose your metrics

Tick a metric to use it in the risk rating:

• Combined share - the merged entity's share of the local market.

• HHI score - the Herfindahl-Hirschman Index, a measure of how concentrated the market is (0 to 10,000).

• Fascia-count - how many competing fascias are in the market before and after the merger (e.g. "13-to-12").

Click Add metric for more options:

• Combined rank - the merged entity's rank in the market.

• Top-1 to Top-5 share - the combined share of the largest one to five players, a measure of overall concentration.

Step 2 - Set the thresholds

Each metric you switch on has two settings:

• The slider - drag its two handles to set where Low, Medium and High risk begin. In the example below, a combined share under 25% is low risk, 25% to 33% is medium, and above 33% is high.

• Delta threshold - the smallest change the merger must cause for a market to be rated at all, e.g. 5pp (percentage points) of combined share. Markets where the merger changes the metric by less than this are marked Low delta.

If you use several metrics, each market takes the highest of its ratings. For example, a market that is medium risk on combined share but high risk on HHI is rated high risk.

Step 3 - Review markets by risk

The markers on the map change colour to show each market's rating, and buttons above the map show how many markets fall into each group:

• High risk, Medium risk and Low risk

• Low delta - the parties overlap, but the merger changes the metrics by less than your delta thresholds

• No overlap - no site of the other party falls inside the market

Click a button to show or hide that group on the map and in the Table view. The count at the top of the map tells you how many markets are shown. Open the Selected local market tab to look at any market in detail.

Risk ratings in your download

When metrics are switched on, the Download settings window offers a Risk rating option that flags each market by its rating in the workbook. You can also limit maps and charts in the download to high or medium-and-high risk markets.

Pro tips

• Align your thresholds with the guidance or precedent of the authority reviewing the deal.

• Try a few threshold settings to see how many markets move between groups. The ratings update instantly, without re-running the scenario.

• Use the delta threshold to set aside markets where the merger makes little difference.