These bonds are hybrids 25: debt in good times but convertible into equity 26 when common equity becomes too small relative to banks' balance sheets.

这些债券都是混合型证券：行情好时是债券，但是当银行的普通权益相对于银行资产负债表过小时，可以转化为权益。

youdao

Under the classical gold-coin standard (1717-1914) private banks and central banks alike issued currency convertible into a fixed weight of gold, with balance sheets consisting primarily of gold coins and short-term loans denominated in local (but gold-convertible) money.

FORBES: Gold, Reagan and the Reds: From Degraded Dollar to Downgraded Debt

One is through the wider use of convertible bonds which automatically switch into equity, bolstering the bank's balance-sheet if, for instance, its capital ratio falls below a trigger threshold.

ECONOMIST: Dealing with bad banks