Priced at $14.25 (£11.22), Old Mutual said the money raised from the sale of shares in US-based OMAM will be used for “general corporate purposes”.
As well as a sell-off of shares, Old Mutual will further reduce its stake in the asset management firm and sell six million shares back to the OMAM as part of a repurchase transaction.
The news comes after Old Mutual announced the decision to break up into four separate businesses in March this year.
At the time of the announcement, chief executive Bruce Hemphill said the four separate businesses would “flourish independently” once they were free from the costs and constraints of being within the group.
He added: “Our new strategy will allow each business to have simpler access to capital markets to fund its growth more easily and be valued more appropriately, with more straight forward regulatory arrangements.”
The four-way break up would see the FTSE 100 business separated into Nedbank, Old Mutual Wealth, Om Asset Management and Olm Mutual Emerging markets as early as 2018.