But individuals, too, are doing what they can to protect themselves. At night, many of them are walking the city in search of A.T.M.s that have not been emptied of cash. Others are using computers to spread money to various accounts or to relatives, lowering the total in each account.
With banks closed, Greeks are limited to withdrawals of €60, or $66, a day from A.T.M.s and cannot make international transactions, factors that have gutted some businesses already.
The auction at the downtown fish market, where cash is mandatory, was sparsely attended Wednesday, leaving fishermen fretting. But there are more mundane problems, too. The A.T.M.s give out only €20 and €50 notes, and they appear to be running out of €20s. Stores are having an increasingly difficult time finding change.
Some businesses have begun yet another round of layoffs. "My boss came in and said, 'We are all going to die,' " said a young woman who works for a small travel agency in Athens. "He gathered us all together, really, to tell us that."
He then reduced her hours to two days a week, she said, adding that her boss "was completely, totally panicked."
The agency has been unable to issue tickets this week because Greek travel agents have been blocked from the global ticketing system.
Pharmacists began to feel the pinch almost immediately when the banks shut down, because most drugs are imported and they had no way to pay for them. Michalis Moschonas, an Athens pharmacist, said his customers had been concerned, if understanding, when he had to turn them away. He was also understanding, allowing many people who were unable to get enough cash to pay for their medicine to owe him money.
"I have countless i.o.u.'s behind my counter," he said.
A contractor at a Greek energy company, who spoke on the condition of anonymity, said his firm had paid all its taxes for the year last week to whittle down the funds that could be subject to a deposit tax.
"I'm even thinking about buying a car, although I don't need one, to get my cash balance lower," he said. "People want their money in physical assets, not in the bank."