Announcing its quarterly results, AMP said the three per cent decline in AUM to $111.1 billion can be attributed to "negative investment market movements during the quarter".
According to a statement, the wealth management arm also recorded a decline in cash flows for the third quarter, down from $476 million in the previous corresponding period to $241 million.
The statement indicated that the decline in cash flows were driven in a "large part" by the closure of its Genesys Wealth Advisers dealer group.
"Cash flows were also impacted by increased investment market volatility and continued implementation of the FOFA reforms," the statement said.
"Internal inflows were $4.3 billion in Q3 2015 ($5 billion in Q3 2014), representing 57 per cent (61 per cent in Q3 2014) of total cash inflows."
AMP also said retail net cash flows into its platforms dropped eight per cent to $707 million in the third quarter, down from $771 million in the third quarter of last year.
"Lower adviser cash flow activity impacted cash inflows during the quarter and higher pension payments mitigated the benefit from retention activities," the statement said.
"AMP's leading wrap platform North reported net cash flows of $1.1 billion in Q3 2015, down 24 per cent from Q3 2014. Over 60 per cent of North's net cash flows were externally sourced.
"North AUM grew to $19.1 billion at the end of the quarter, up three per cent from $18.6 billion at the end of Q2 2015 (and $13.8 billion at Q3 2014)," it said.
AMP's wealth protection business reported a three per cent increase in in-force annual premiums to $1,972 million.
"The third quarter result for the Australian wealth protection business was impacted by claims experience losses primarily relating to the retail income protection book," the statement said.
"This negative experience has not given rise to any revised best estimate claims assumptions for the retail income protection book."
