The group reported £2bn of outflows in the first six months of 2016, and a fall in pre-tax profit to £100m from £117.4m in 2015.
In its interim results the firm reported a 3% increase in its assets under management to from £92bn at the start of the year to £95bn, reflecting £5.1bn of market and FX movements, but underlying pre-tax profit decreased due to lower performance fees. They fell from £48.8m to £20.1m - a 59% drop.
The group's retail outflows "accelerated considerably in the immediate aftermath" of the UK's vote to leave the European Union -particularly from the Henderson UK Property fund, which ceased trading on 5 July after significant outflows, and funds focused on European assets.
Henderson's European equities products lost £1.2bn in assets during the six months.
“The first half was dominated by widespread market uncertainty in the run up to the UK referendum, said Andrew Formica, chief executive of Henderson.
"Clients pulled back from investing in European assets and UK property, particularly after the referendum result, but we saw good demand for absolute return and income generating investment styles,” he added. The group's absolute return strategies recorded £734m in retail flows.
"The dislocation caused by the UK referendum result demonstrates the importance of continuing to diversify our business," continued Formica.
Henderson’s share price rose 4.13% today to around 232p.