That sounds like a sales tax, no? Which would be regressive unless you charged sales tax on purchase of debt / equity. Doesn't matter if it's only a sales tax on yachts or whatever because they would have to buy like every single yacht to come close to comparing with their spending on further means of production as expressed by ownership / debt.

Edit: Honestly, I'm not sure if it would stop being regressive even if there was sales tax on buying stock or whatever. Mostly going off vibes with that one.