Those who went to work at the start of the Iranian week on Saturday saw their money shed a quarter of its value by the time they left the office Wednesday. Signs of the currency chaos can be seen everywhere in Tehran, where travel agents offer vacation prices only in hard currency and diapers have disappeared from store shelves — something acknowledged by the supreme leader.

Many exchange shops in downtown Tehran simply turned off their electronic signs showing the current rate for the U.S. dollar, while some Iranians who wanted hard currency sought out informal money traders on street corners. Exchange shops that remained open offered 150,000 rials to the U.S. dollar.

"Everyone's just nervous," said Mostafa Shahriar, 40, who was seeking dollars.

There was no immediate acknowledgement of the drop on state media.

Iran's economy has faced troubled times in the past, whether from the shah overspending on military arms in the 1970s or the Western sanctions following the 1979 Islamic Revolution and U.S. Embassy takeover. Drastic fluctuations in oil prices have also taken a toll.