Industrial conglomerates went out of fashion some 15 years ago, as they could not prove that it is better to make rather than buy.

But financial conglomerates soldiered on and, in fact, grew in importance. But just as the recession of the early 1990s led to hard questions on what industrial corporations should be doing, the recent financial meltdown has thrown up its own doubts about whether financial conglomerates really create higher profit margins and shareholder value.

Citigroup is, perhaps, the best known advertisement for the benefits and pitfalls of the financial supermarket. Its all-too-frequent trysts with near-bankruptcy—most recently in 2008—have taken a lot of sheen off its business model.

Now comes the news that ING Group is going to be sliced into two. Its banking and insurance businesses are going to be separated. ING is one of the poster boys of bancassurance, the idea that there is great synergy in selling insurance through bank branches owned by the same group. That, too, is now in question.