The European Central Bank's (ECB's) chief supervisor on Thursday supported creating global standards for convertible bonds that were wiped out as part of Credit Suisse's rescue by rival UBS earlier this year.
Holders of Credit Suisse's Additional Tier 1 bonds with a notional value of 16 billion Swiss francs ($18.1 billion) lost their whole investment while stockholders received some shares in UBS - a differential treatment that triggered lawsuits and sent shockwaves through financial markets.
ECB chief supervisor Andrea Enria backed the decision by Swiss authorities, which reflected clauses enshrined in local bonds, but urged global standard-setters on the Basel Committee on Banking Supervision to put some order in this market.
"It would be good if the Basel committee could in future think further on some standardization of contracts in these areas," Enria told the annual conference of the European Systemic Risk Board.
"Adding some common features, I think, would be beneficial to avoid that there is a sort of contagion between different instruments and that everybody understands how they work in times of stress."
Speaking on the same panel, the Basel Committee's chairman Pablo Hernández de Cos said the issue was "on the list".
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The Basel Committee said in a report last month it would review the features of AT1 bonds, including the "loss-absorbing hierarchy".
Shares are generally regarded as junior to bonds, meaning they suffer losses first in a crisis. But Credit Suisse's bonds contained a clause allowing authorities the write down those bonds without winding down the bank.
This clause is not a feature in bonds issued by European Union banks and the ECB has made clear that it would impose losses on shareholders first.