It's complicated.

The precise chain of events is:

1) 2006 Father of wife sells Toyota dealership at a very favourable price to a consortium of business men who use a bank loan to pay for it.

2) Wife inherits/is given money by father.

3) Wife uses some of the money to invest in Icelandic Banks using an offshore company Wintris. Note, Icelandic Banks are desperately raising capital during this period ... in order to allow them to make more loans. At the same time, Banks are also borrowing heavily from abroad, and re-lending that money to a small circle of businessmen (see 1).

4) Banks go under because during 2008 they are unable to rollover the loans that they have borrowed on the international credit market (see 3), and also are starting to experience massive defaults on the loans they have made to a small circle of Icelandic businessmen (see 1 & 3).

5) Wintris is listed as one of many creditors to the Icelandic Banks, and and consequently stands to benefit (or not) from the resolution talks that are ongoing to this day.

TL;DR: He and his wife have an enormous stake in how assets of the (now nationalized) banks are handled, a policy controlled by his government.

He chose to hide this ridiculous conflict of interest, not only by holding secret off-shore companies, but also by promoting legislation on what government officials are required to disclose.

Well, the stock was owned before the banks collapsed, so no matter what it's a loss. The only "benefit" you could get is trying to get back as much of your investment as you can.. in which case this begs the question, would these holdings have influenced decisions in things like deciding whether the failed banks should repay the debt owed to the UK / Netherlands, etc.