Rebello (pictured) was previously head of passive distribution for the UK, Ireland and the Channel Islands for five years until August.
She joined DWS from BlackRock where she was part of the iShares UK sales team between 2013 and 2015.
Rebello started her career at HSBC in the structured equity derivatives sales team where she spent eight years from 2005.
Her replacement as head of UK passive distribution is yet to be announced.
Mistry was replaced by the firm’s global head for systematic investment solutions Fiona Bassett.