Ann: Investor Update Presentation & Confirmation of FY18 Guidance, page-290

Ah, how about this for a theory...

Vocus is likely to be booted out of the ASX100 on the 15th December (3rd Friday in December) due to its reduced market cap, it probably should have been removed last quarter. Notice is given one week prior for December, which is the 8th.

When the rebalance happens ETF and other funds will likely reduce their holding, the last few red days could be some getting in early, trying to sell before others do.

If that is the reason, we might have a few more red days yet, but its a one-off, and it doesnt effect the long term value of the business.