The relationship turned ugly in early 2014, when Elliott put in a bid to buy the whole company and claimed that management was making "highly misleading statements" to shareholders about the level of buyer interest.
Eight years earlier, Kennelly led a hot networking IPO. Now he found himself burdened by public investor demands.
"The problem is that as you get bigger and you have to pivot and do different things, it's harder in the public eye," said Kennelly. "The main value that Wall Street puts on a company is really on short-term revenue growth."
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Thoma Bravo finally acquired a majority of Riverbed for about $3.6 billion in April, winning the bid over eight other investor groups and getting Elliott off Kennelly's back. The deal included $2.1 billion of debt.
Riverbed, out of the public spotlight, has revamped its own deal engine, announcing this week the acquisition of Ocedo to expand in software-based networking.
For Thoma Bravo, the Riverbed opportunity would likely not have popped up without activism, because the company's board didn't want to sell and Thoma Bravo prides itself on being management friendly. In other words, it doesn't go hostile.
"We're seeing companies being much more open to it," Boro said. "Public markets can be tough for businesses going through changes."
The firm has a long history with Elliott: Riverbed, Compuware, Novell and Blue Coat were all pressured by the hedge fund before selling.