Need more information about that volume to have an opinion. e.g. was it a special crossing out of hours? [that will happen when a large holder is selling to a specific buyer... e.g. when an institutional holder wants to exit their position and they have found a buyer for the entire line of stock]...if not, did it occur on the same day as an announcement? The price candle is very short and there doesn't appear to be much change afterwards...
From time to time you do see odd trading patterns and events. Some are suspicious and others just due to the weird ways of people.
@Freehold put up a post today on the AVZ thread where he discussed the 'wildwest' nature of the ASX... bodies like ASIC have the necessary laws but its woefully underfunded to do its job ... meaning ... when manipulation does occur its usually very blatant... not nearly as subtle along the lines of tickling the TA as you are thinking.