I wouldnt have thought that this process should have much of an effect on CDU other than the inflated opening auction volumes. Take the SPDR® S&P/ASX 200 Fund - on which some of the Share based investment bank accounts are based. They have a holding of only 542 CDU shares - and that is a 2 billion dollar fund.
I guess there could be many more funds with exposure to CDU which would amplify this however.