The wealth manager’s share price was down 7.51% at 2pm, after recovering slightly from an initial 10% drop.
It is thought the fall in its share price came after rumours were circulated about Rathbones in an online chatroom.
The firm denied the rumours and said it was taking action to address the possibility of market abuse.
In a stockmarket announcement it said: “Rathbones notes the movement in its share price this morning which coincides with an anonymous allegation made in an online discussion forum.
“We are not aware of anything that would give substance to this allegation and are taking strong action. We are alert to the possibility of market abuse.”
