Ann: FY16 Results Ahead of Guidance - Revenue and EBITDA up-MBE.AX, page-97

I suspect CBA's investment thesis is a touch more comprehensive than "hey, look what the rest of the market is doing! Better sell out."

The past two days have left professional analysts of good repute positively flabbergasted as to why this has retreated. To this moment there isn't really any compelling reason that I've read. It could be a large holder taking a profit on it's investment that has caused a snowball effect with smaller retail guys.

Sometimes the market is fickle and presents buying opportunities. Not the first or the last time something like this will happen.