'Anonymous' is any brokerage house that makes this choice when buying or selling. You can have a broker buying publicly as house XX and doing transactions at the same time as house ANONYMOUS. A buyer or seller may also request that their transaction be done using Anonymous. The Anonymous results for one day may be a single house or the results for dozens of traders. One group of houses may do a lot of transactions one day and the next day it may be another group. Add in that someone may buy on one exchange and sell on another. For that reason you can't read to much into who is buyng and selling.

... Been There