> This — a “7% trigger permanent write-down AT1” — is not the only way for an AT1 to work, though it is the way that Credit Suisse’s AT1s worked. Some AT1s have different triggers. Some AT1s convert into common stock when the trigger is hit, instead of being written down to zero; others are temporarily written down (they stop paying interest) when the trigger is hit, but can bounce back if the equity recovers. (Here is a 2013 primer on CoCos from the Bank for International Settlements.)
> These securities are, basically, a trick. To investors, they seem like bonds: They pay interest, get paid back in five years, feel pretty safe. To regulators, they seem like equity: If the bank runs into trouble, it can raise capital by zeroing the AT1s. If investors think they are bonds and regulators think they are equity, somebody is wrong. The investors are wrong.
> In particular, investors seem to think that AT1s are senior to equity, and that the common stock needs to go to zero before the AT1s suffer any losses. But this is not quite right. You can tell because the whole point of the AT1s is that they go to zero if the common equity tier 1 capital ratio falls below 7%.
> ...
> That's the trick! The trick of the AT1s — the reason that banks and regulators like them — is that they are equity, and they say they are equity, and they are totally clear and transparent about how they work, but investors assume that they are bonds. You go to investors and say “would you like to buy a bond that goes to zero before the common stock does” and the investors say “sure I’d love to buy a bond, that could never go to zero before the common stock does,” and the bank benefits from the misunderstanding.
[1] https://www.bloomberg.com/opinion/articles/2023-03-20/ubs-go...