I'm not Swedish, but I find this area relatively interesting. The idea is fairly straightforward: Sweden's model created low income inequality between the poor and the rich, but did not create low wealth inequality. A large proportion of Swedish capital was controlled by 15 families, and most wealth his still controlled by a small inherited class (many descended from the old Swedish nobility), and 80-90% of wealth is passed down. We might think of Sweden's long period of dominance by the Social Democrats from the 1930s - 1970s as a sort of bargain between the lower/middle and upper classes: pay your workers well, ensure a strong welfare state, don't be too ostentatious and the lower class will let the upper class run their businesses as usual. One family, the Wallenbergs, controlled ABB, Ericsson, Electrolux, Atlas Copco, SKF, AstraZeneca and Saab. In the 70s they employed 40% of Sweden's workforce and were 40% of Sweden's stock market's worth.

https://econlife.com/2016/04/swedish-wealth-distribution/
http://marginalrevolution.com/marginalrevolution/2014/05/wea...

For Socialists, this led to an obvious question: what should be done about this? Their solution: most of this wealth comes from ownership of Capital in Sweden's large firms (this is an important distinction between Sweden and Denmark - Sweden has many more large corporations). Workers represented by the trade unions would own a large share of capital and then redistribute the profits from capital back to the workers (and reinvest in the firm and in worker training and investment in new firs controlled by workers). I think this is a relatively interesting take on the idea of "worker controlled enterprises". A very leftist take on all of this is here:
https://www.jacobinmag.com/2017/08/sweden-social-democracy-m...

Of course it didn't happen, as part of the larger global ant-left backlash beginning in the late 70s which took basically everyone by surprise (see also The Iranian Revolution, the American Evangelical movement, Likud, the rise of the BJP in India...).

It's still an interesting idea, I think made more interesting by the rise of index funds like Vanguard. Increasingly capital is controlled by a small group of massive investment funds whose goal is to do nothing. This has led to the half-joking idea that index funds are worse than Marxism. I'll let Mark Levine explain:

" Virtually no one that I talk to in or around the financial industry really believes the "common ownership of companies by mutual funds undercuts competition" theory. It just seems too attenuated: Sure, it might be in BlackRock's and Vanguard's interests if the companies they own don't slash prices to compete with each other, but it's not (usually) like they call up executives to tell them that. Plus "competition" is usually a more nebulous concept than price-cutting: It might be in shareholders' interests to keep prices high, but it is also in shareholders' interests to see more innovation and more competition on quality. If you own the entire economic pie, your interest is in growing that pie, not in keeping each company's slices the same. And the way the pie grows is through the normal capitalist processes of innovation and competition and creative destruction and so forth.

Still I am so desperately fond of this theory. What I love -- what is made so clear in Jacobin's discussion -- is how it wraps capitalism all the way around to socialism. Index funds are in many ways a perfection of financial capitalism: Not only are they the result of scientific finance (modern portfolio theory, the efficient markets hypothesis, etc.) replacing earlier and less rigorous forms of investing, but they also concentrate and align shareholders with each other, and corporate managers with shareholders, in a way that seems like it would be well suited to "ensure that corporations remain within capitalist logic." And the result is something that both Marxists and also financial analysts think is quasi-communist, that "undermines the basic logic that made capitalism an economically and politically successful system in the first place." What if Marx was right that capitalism would ultimately destroy itself, but the way that it does so is through index funds? "

https://www.bloomberg.com/view/articles/2017-10-26/maybe-ind...

https://www.bloomberg.com/view/articles/2016-08-24/are-index...
(this essay is also fun because he discusses the hypothetical "Best Planning Robot", a computer so good at allocating capital it finally solves all of Kantorovich's problems)

Anyways, all of this sort of suggests on silly idea: why not just wait until Vanguard controls most of the stock market and nationalize it? I don't think anyone believes this, but it's certainly something to think about.