The offer represents a 32.4 percent premium to UNIT4's closing price on October 11, just before it announced it had been approached by companies interested in buying it.

The two companies reached a conditional agreement on a recommended full public offer of 38.75 euro (with dividend) in cash per issued and outstanding ordinary share of UNIT4.

While UNIT4 recommended the offer to shareholders, it also said both parties had the option to terminate the deal if a third party made a substantially higher bid.

"Advent is an experienced investor globally in the software industry and locally in the Netherlands and will provide UNIT4 with financial backing, expertise and support for capital expenditures, investments and acquisitions in accordance with UNIT4's long-term strategy," UNIT4 said in a statement.

(Reporting by Sara Webb; Editing by Louise Ireland)