The FTSE 100-listed firm saw its pre-tax profit jump to £940mln in the six months to the end of June, up from £534mln a year earlier, as revenue rose to £10.82bn from £7.48bn.
The group said its profit was boosted by sterling weakness in the first half, while Old Mutual Wealth had a strong six months and Old Mutual Emerging Markets and Nedbank traded "resiliently" despite "continuing difficult macroeconomic conditions" in South Africa.
OM Asset Management, which is now an independent business, saw its pre-tax economic net income rise by 27% to US$11mln.
Old Mutual sold a 45% stake in OM Asset Management at the end of March for US$785.0mln as part of its "managed separation" plans to "preserve and release the value currently trapped within the group structure, as well as creating additional value by driving enhanced performance by the underlying businesses".
The firm said it remains on track to deliver that managed separation within stated timing and costs.
Making “excellent progress” in delivering managed separation
Old Mutual’s chief executive Bruce Hemphill said: "We are making excellent progress in delivering the managed separation of Old Mutual having materially reduced debt and largely disposed of our stake in OM Asset Management.
“Our focus for the next phase of managed separation is first to finalise the appropriate standalone balance sheets for our two unlisted businesses and second, subject to the necessary approvals, deliver them to our shareholders at the earliest opportunity in 2018 after our 2017 full-year results,"
Old Mutual will pay an interim dividend of 3.53p, up 32% on last year’s pay-out.