M&G's retail business was particularly badly hit, with net outflows for the quarter of £3.9bn, compared to net inflows in its institutional business of £1.2bn.
Share price in the company dropped to a low of 1,514p, down 2.3 per cent, shortly after the results were revealed.
The company also posted profits from new business of £574m, up 16 per cent, or 14 per cent on a constant exchange rate basis, compared with £496m for the same period last year.
Profits from new business for the year to date also rose, up 17 per cent, or 13 per cent on a constant exchange rate basis, to £1.8bn. Group new business profits for the year to date for the same period last year were £1.5bn.
And sales for the group also grew, with annual premium equivalent sales of £1.3bn for the third quarter, compared to £1.1bn for the same quarter last year. Sales for the group for the year to date were £4bn, compared to £3.4bn for the same time last year.
These results are the first full set of results presided over by new group chief executive Mike Wells, who replaced Tidjane Thiam on 1 June.
Wells said: “This performance reflects strong growth in our Asian and UK life operations and continued new business discipline in the US, reinforcing the diverse and resilient nature of our business during a period of significant global instability.”
He continued: “Overall, our strong performance in 2015 continues to demonstrate the successful execution of our strategy in pursuing clearly defined long-term opportunities in Asia, the US and the UK. We remain optimistic about the outlook across the group, particularly in Asia where the compelling long-term fundamentals of the region are unchanged.”