Economists proposed in the past a Financial Transaction Tax. Ten years ago left wing activists campaigned for that. Now conservative politicians. Still people doubt if that’s a good idea to prevent excessive trading or would even distort the markets. The political debate may lead to other considerations.
Elsewhere I commented:
The point is not whether the proposal makes much sense, it is simply that there are no other proposals offered… Get us another stone and a bird to kill. You could also view the FTT as a service fee for financial security externalities of the market borne by the public sphere.