Netherlands-based Unit4 provides business software for human resource management, financial planning, accounting and others, its website showed. It was taken private when Advent bought it in 2014 for around 1.2 billion euros ($1.43 billion).
Founded in 1980 and led by Chief Executive Officer Mike Ettling, Unit4 partnered with Microsoft in 2015 to create self-driving business applications.
Ettling will continue to lead the Unit4, the business software maker said.
Advent revived plans to sell Unit4 after receiving interest from a special purpose acquisition company, Bloomberg News reported in November last year.
Investment manager Partners Group has also agreed to invest in the deal.
TA Associates, which has U.S. offices in Menlo Park and California, backs companies in the business services, consumer, financial services, healthcare and technology sectors. It has raised $33.5 billion in capital since its founding in 1968.
It has invested in over 500 companies, and its portfolio includes ATM operator Cardtronics Plc and database software firm Idera, among others.