So I have found the culprit who dumps AMG shares each time it goes up.
Its the Chinese, through Moly Mines who in turned acquired QMN end of last year/ earlier this year.
If you look at AMG 2017 annual report, QMN held 12.5m shares. In the 2018 annual report, they are no longer listed as part of the top 20.
So I guess the good news is they have or almost ran out of shares to sell, for whatever reason that we probably wouldn't find out in our lifetime!