Key facts

Formula: Brand promotional activity divided by total market activity, times 100
Common inputs: Sales calls (details), samples, media spend, digital impressions
Paired metric: Share of market (SOM), such as TRx or NBRx share
Market definition: Set by the analyst: drug class, indication or competitive set

What is share of voice?

Share of voice measures how much a brand promotes compared with its competitors. If three brands in a class deliver 6,000, 3,000 and 1,000 sales representative visits (details) to the same prescribers in a quarter, the leading brand holds a 60 percent share of voice for personal promotion.

Pharmaceutical SOV can be measured for one channel or blended across channels. Common versions include share of details, share of samples, share of journal and media spending, and share of digital impressions or emails sent to healthcare professionals.

In social listening, SOV sometimes means the share of online mentions a brand receives, including posts the company did not create. That version measures conversation rather than company-controlled promotion.

How share of voice is measured

Building an SOV figure takes three choices:

Promotional activity data for competitors typically comes from panels of representatives or clinicians who report their interactions, or from media monitoring, so SOV figures are estimates. Two sources can report different shares for the same brand.

Define the market: the competing brands, often the products approved for the same indication.
Choose the activity measure: details, samples, spend or impressions, each with its own data source.
Set the audience and period: all prescribers or a target segment, by month or quarter.

Why share of voice matters

Brand teams compare SOV with share of market (SOM). A brand whose SOV runs well above its prescription share may be investing ahead of growth, as is common at launch, while a brand with SOV far below its share may be exposed to competitors. Competitive intelligence teams track competitor SOV for early signs of a launch push, a new indication or reduced support ahead of loss of exclusivity.

SOV is an input, not an outcome. More promotion does not guarantee more prescribing, and every promotional activity counted in SOV must stay within the product's approved labeling.