After the completion, Cello will own an 11.3% stake in the UK-based software provider.
Pulsar, which has gross assets of £3.2mln, will still work for Cello in cases of “mutual client opportunity”.
The AIM-listed health advisory group said the sale would enable it to concentrate investment in the expanding healthcare section as well as Signal, its marketing services division.
“Post the exit of Facebook in 2017 as a data provider, general growth in this social media analytics market has been slower,” Cello said in a statement.
Mark Scott, chief executive of Cello, commented: "We are delighted that Pulsar can now begin the next stage in its development as a business whilst enabling Cello to focus on its core healthcare activities. We look forward to the ongoing partnership with Access Intelligence, both as a shareholder and as an ongoing user of Pulsar."
Shares were flat at 127.06p at noon.