It's straight up idiotic. Australia is an overregulated country, but at least they don't have taxes on monetary trading activities. There is already, probably, a capital gains tax, similar to Australia, in Spain, and sure, if you even support the idea of taxation at all, then it certainly should not apply to speculative values of held assets, only when they are converted into cash. Otherwise you are killing the golden goose.

Obviously, this is spanish politicians trying to find ways to compensate for how badly they are strangling the national economy...