Still, because trade finance is short-term— usually 30 to 90 days—and backed by collateral, lenders have some recourse.
Natalie Blyth of HSBC, a bank, reckons that the performance gap between trade-finance assets and corporate loans will widen.
The third problem is a possible crunch in new financing.
To assess clients, banks and insurers rely on credit ratings. These have plummeted as firms' cash flows have dwindled.
The resulting squeeze may linger, says Ebru Pakcan of Citigroup, a bank; firms are downgraded quickly, but upgraded slowly.
Some lenders may focus on large clients or exit some markets entirely.
Insurers have cut their exposure to the industry by 8-9%, about half as much as in 2008-09.
In emerging economies, sovereign downgrades have also pulled down corporate ratings, says Marc Auboin of the World Trade Organisation (WTO).
On July 1st the WTO and six multilateral banks promised to alleviate trade-finance shortages.
Still, the damage could have been worse. Thankfully, banks have sturdier equity buffers than in the last recession.
Since 2016 Coface has raised its solvency ratios—insurers' equivalent of banks' capital-adequacy buffers—from 150% to 190%, says Xavier Durand, its boss.
Central-bank action has shored up lenders' finances.
Governments in Europe have let export-credit agencies cover short-term trade, and have offered insurers backstops.
The question is how long the support lasts. Banks and insurers will see their capital eaten up as loans sour.
Government aid could be withdrawn too soon, worries Alexis Garatti of Euler Hermes, a trade-credit insurer.
贸易信贷保险公司Euler Hermes的Alexis Garatti担心，政府可能会过早取消援助。
Support could be taken away just as the demand for finance returns.
As new orders work their way through supply chains, exports appear to be bouncing back faster than manufacturing.
Still, the pandemic could lead to lasting gains by forcing the industry to digitise.
Alexander Goulandris of Essdocs, which promotes paperless trade,
says 60 chambers of commerce have opted for its electronic certificates of origin in recent months, compared with the usual rate of ten a year.
Some countries have also adopted laws recognising the validity of e-documents.
Digital standards could make it easier to bundle trade-finance loans into securities that can be sold on to institutional investors, providing more oxygen to commerce.
Trade finance has long followed outmoded practices. Now might be its chance to blow everyone's socks off.