According to social analytics firm Quintly, daily brand posts on Facebook increased by 36% last year while posts on Instagram, the image-sharing site owned by Facebook, rose 14%. Over the same period, the number of posts on Twitter slipped by 2%.
Quintly reached these findings after analysing 180,000 profiles on the three social media networks for its Social Benchmarking Study.
As well as revealing that brands increased their activity on Facebook in 2015, the study found that Instagram achieved the highest follower growth because it is not as "saturated" as Facebook and Twitter.
"Due to the described fact that Instagram is still on the rise in terms of the number of users and daily posts, it makes sense that businesses ramp up their activities there," advised Alfroza Irin, a social media analyst at Quintly.
"On Facebook, the strong increase is a sign that Facebook is far from being 'dead'. It shows that companies still rely heavily on this network," she added.
While Instagram recorded the highest follower growth among the three social networks, the study found that levels peaked in February and then began trending downwards.
Facebook and Twitter were more stable, the report added, but it described Instagram's slowing growth as "a normal phenomenon" as the network matures.
Instagram also beat Facebook and Twitter in terms of engagement rates, while brands with the smallest number of followers (up to 1,000) achieved the highest interaction.
"This result qualifies the notion that big social media numbers do not mean big activity," Irin explained. "Followers of the smaller profile are more focused and interactive."
Data sourced from Quintly; additional content by Warc staff