Can somebody tell me why, when they're talking about those fancy financial products, people use the word "tranche" rather than "slice"? No big deal, I'm just curious.
例の手の込んだ金融商品をみんな「スライス」ではなく「トランシェ」と呼ぶけれども、その理由を誰か知っている? 大した話じゃないけど、気になったので。


'slice' is already used to mean a portion of a large order that is allocated to a particular venue for trading. Which sort of implies that all slices of a particular pie are all composed of the same underlying security.

Tranche is exactly the opposite - the different tranches are specifically different. They have been called 'levels', but that implies that one is better than the other. And tranche is a euphemism for level.

? - Statistical Modeling, Causal Inference, and Social Science

Possibly because "mezzanine tranche" sounds nicer than "first slice."

I'm going to take a real stab at it though. My understanding is that post-1790s and into the early 1800s that after paying for wars; the expenses forced on them by foreign commissions during their occupation; some bad investments etc that France was running extremely large debts. Around 1815 - 1820 France started looking around for foreign loans to help them. Because of France's massive debt (it was running above 300 million francs, if I remember correctly, which was obviously massive at the time) and investors were very skeptical (I would be too with such a large debt!) and so rather than bearing the risk all too themselves they diversified the risk by slicing and dicing up the loan - essentially tranching (though quite different than modern tranching, but it was the same principle). My assumption is that the French called them "tranches" because the loans were being sliced up and because the French were engaging in such large amounts of tranching, more than any other borrower in financial history, that the term naturally migrated to other financiers in Amsterdam and London and translated around the world from there. I suspect Salomon Brothers in the 1980s just picked up the old term in the context of collateralized mortgage obligations since the concept of slicing up an underlying security was somewhat similar to old-style tranching.

That's hardily a rigorous history since I don't know who came up with the idea of tranching nor do I know if the term really was transmitted around the world, but it seems plausible given that investors were very aggressively engaging in a form of tranching with France very early. Furthermore, tranching was not at all common practice (and, in fact, wasn't particularly common until the 20th century) and so such excessive amounts of it (relative to the time) might have given France claim over the terminology. Maybe an economic historian could trace the origins of the term better than I could though.



? - Statistical Modeling, Causal Inference, and Social Science

*1:[2010/4/23追記]wrong, rogue and booklogで本エントリを取り上げていただいたが、そこで紹介されている話もこれに近い。