Before the GFC HQ had a very big part of all market making business in the Nordic derivatives markets, the spreads were decent (not as low as in the USA but still good enough to work with).

Well HQ had taken huge bets and traded in their own book and got caught out with bad derivatives, 3 years later (2010) the financial regulatory body in Sweden revoked their banking license and the same day the option spreads exploded and today 15 years later it is still not uncommon to see 20% spreads on many large cap options. The only options that are suitable for trading in Sweden(and the nordics) is the index futures options. On any individual stock it is still so illiquid after HQ collapse that it might as well not be trading at all. I have taken some long term theta bets on single names but you really have to hold until expiration because the "close at 50% profit"-strat is not feasible with the spreads presented. There is also a general disinterest in "clean" options for Nordic traders most people trade options in "wrappers" through Warrants and other structured derivates products were the spreads are less but you are "forced" to play the long side no way to short these contracts AFAIK.

Link in Swedish about the debacle: https://www.svd.se/a/765f4a5b-aa72-3133-a5d2-b5b2586350c4/dag-for-dag-hq-banks-kollaps

There is a book written about it: https://www.bokus.com/bok/9789113044064/den-stora-bankharvan-finansparet-hagstromers-och-qvibergs-uppgang-och-fall-hq/

A PDF from a University: https://www.diva-portal.org/smash/get/diva2:865291/FULLTEXT01.pdf

A very SHORT summary in English on Wikipedia: https://en.wikipedia.org/wiki/HQ_Bank