Anonymous....Anon....House 001....All refer to someone who does not want you to know which broker/house is buying or selling.
Your average retail investor does not use anonymous, as it's typically for advisers or professional traders who have a larger following. You can check with your broker to see if they can do it for you.
The most common use for anonymous is when a broker or individual wants to unload a large position, or part of a position, without investors knowing who is doing the selling. For example, if we knew that a private placement was just done by Northern Securities, and then we start seeing Northern Securities selling, this would be viewed as the smart money selling and could cause others to follow suit. By Northern Securities selling under anonymous, it makes it a little less obvious on who is doing the selling. The main reason why anonymous selling is allowed by the TSX and TSXV is to try and reduce the impact on the pricing. It is up for debate on whether that is the result or not.
Other uses for anon are....
--> To accrue a position discretely.
--> To spook people by selling via anonymous to make a stock look more bearish than it actually is.
--> To make a stock look artificially strong by accruing a position via anonymous.
--> To use it on one end of a trade between the same house. For example RBC buying, and RBC selling, but disguising the sell as anonymous. This can artificially push a stock higher or lower but the net change to the broker/house is zero. This disguises who is on the selling end.
Something to keep in mind is that even if an insider goes under anonymous, the trade is still reported to the exchange and you can view the insider transaction at the end of the day, or via Canadian insider a couple days later.
Looking to see what anonymous is doing is one of my top 5 things to look into when thinking about buying a stock. If I see anonymous selling it for more than 20% of the average volume I typically won't touch it.
Conclusion
Anonymous selling or buying is something to consider as part of your DD. Try to figure out whether it's someone trying to hide their identity, or someone trying to play games. This is one of many tools that can be used when doing your DD.