The firm says the target is now unrealistic after the plunges in global markets and increased volatility.
It says: “A number of the assumptions that underpin our stated goal and which are beyond management’s control are no longer valid, resulting in pressure on assets under management and fee income.”
The company says it will take action to protect the business and profitability and will make a further update in its interim statement on November 6.
In August, Henderson posted an operating profit of £50.8m, a fall of 16 per cent from the £60.5m for the first half of 2007.
Chief executive Roger Yates is stepping down after 10 years, with head of equities Andrew Formica taking on the role. Formica will take the position in November, with David Jacob becoming chief investment officer.