Oct 29 (Reuters) - Henderson Group Plc HGGH.L
* Says assets under management of 81.5 bln stg, down from 82.1 bln at end June, with market weakness outweighing new business gains.
* Says net inflows of 1.3 bln stg, driven by strong performance in retail.
* Says investment performance remained strong, with 82 pct of funds outperforming over three years.
* Says acquisitions of Perennial Fixed Interest and Perennial Growth Management in Australia on track to close on Nov. 1.
* Says expects market conditions to remain challenging and regulatory oversight of asset managers to continue to intensify.
* Says flows remained strong in Q3 at 1.3 bln stg, but were more than offset by market and FX losses of 1.9 bln stg.
* Says net flows into UK retail ranges remained consistent with previous quarters at 400 mln stg.
* Says institutional flows are expected to be negative in Q4, driven by planned roll-off of private equity assets of around 420 mln stg and a net negative short-term pipeline. Further company coverage: HGGH.L