Whilst these bonds can play a useful role in a portfolio, there are some key risks worth weighing.
Again, using the ICE CoCo index as a proxy, the spread on these bonds is currently 206 basis points compared to a median of 385bps. Investors are now being paid very little for the additional complexity of the asset class.
A bank need not repay, or call, an AT1 at its first call date, usually after five years. If it does not, the bond’s maturity extends and the coupon it pays steps up. Many recently issued AT1s have low reset spreads locked in from tighter markets, and because those levels now sit below what banks would pay on new debt, it makes sense for issuers not to call. The bonds then become effectively perpetual, with a duration of 15 to 20 years, four times what was first priced in.
The result is typically limited upside but amplified downside, what the market calls negative convexity. Should markets sell off, the bonds with the lowest reset spreads would be expected to suffer the deepest drawdowns.
Even setting the call question aside, duration is climbing. Almost a quarter of all bank AT1s issued this year carry a ten-year non-call period, double the traditional five. The index’s sensitivity to interest rates, its duration, has drifted up to 3.7 years, from 2.3 in 2023. Many national champions have borrowed for double the usual term at low coupons this year, meaning investors are taking on more interest rate risk from AT1s, on top of their other complexities.
One of the least highlighted risks is the divergence in bond documentation and the subsequent impact on investor protection.
Some AT1 prospectuses contain language allowing the trigger level (threshold at which the bonds may be converted into equity) to automatically adjust upward without bondholder consent. This is structurally more dangerous for holders because this enables the issuer to effectively move the goalposts while the buffer between current CET1 and the trigger narrows. Meanwhile, other AT1 securities which offer more bondholder protection, require a supermajority of holders to approve any amendment to the trigger level.
This kind of difference does not show up at the index or headline spread level. It shows how a bottom-up investor willing to do the necessary due diligence can add value.