I think the idea from the beginning was to issue equity that diluted the current owners, but that was later revised to taxes on profit and payroll. The concept isn't radically different from a pension fund. But of course the purpose was still that workers could take part in the increased profits of companies. The funds weren't allowed to own more than 50% of the voting rights in any company.

There isn't that much in English written about them, but that is actually a good thing since most of it is of good quality.

http://digitalcommons.ilr.cornell.edu/cgi/viewcontent.cgi?ar... https://www.jacobinmag.com/2017/08/sweden-social-democracy-m...