Ann: High Gold Recoveries from Metallurgical Testwork at Grace, page-63

In general ,under normal circumstances they do not. At times of perceived or actual crisis there is an affect that forums can exert.
This can be either to push up as can be seen after some exceptionally positive announcement, when late comers and the opportunistic are drawn to forums for confirmation and comfort pushing up prices above whats reasonable.
Or to push down after an unexpected result causes panic and catches punters unprepared.
At these emotionally fulled times many flock to forums for comfort and guidence. GOD HELP THEM.