You're big on these conspiracy theories-I really don't think CBA have been in the market on either side yesterday or today(as they were so patient on 13.5c) so it would be interesting to know what has stirred up the buying this week-it could be broker research-the copper price is certainly not helping-there are a lot of holders who have bought at much lower prices and it doesn't surprise that some are taking profits as most have losses on other stocks in this lousy market.
