Athex, the main stock index of Athens, plunged to 16.23 percent after re-opening its market following a five-week closure. The top banks of Athens, Piraeus Bank, National Bank, Alpha Bank, and Eurobank, that make up one-fifth of Athex, plummeted to way down the 30 percent maximum allowed, BBC reported. 

Few minutes after it re-opened for trading, it plunged to 22.87 percent. It was still recovering during the morning but fell down to 18 percent during midday. 

The lowest index recorded in the 16-year history of the Greek Purchasing Managers Index went down to 30.2 for July. The most recent time a similar record happened was throughout the 2008 financial crisis for PMI, according to the Wall Street Journal.

According to Nicola Marinelli, portfolio manager for Pentalpha Capital, "For a market that has been closed for five weeks and an economy that is imploding, a [stock market] fall of this scale is the least you can expect."

"People are going to be looking for the big bargain, but I'm not sure this is the time to buy," she added.

This incident is a reflection of the crisis  that Prime Minister Alexis Tsipras has to face as he still tries to discuss terms regarding a third bailout with its creditors as the Greek economy sinks further. 

"The situation in Greek equity markets will have to get a lot worse before it gets better," according to Luca Paolini, chief strategist of London's Picket Asset Management. "There are still critical risks to be resolved," he added, Bloomberg Business reported.

Trading was halted on the Athens stock exchange in late June to control the capital euro outflows that  jeopardizes the Greenk banks' collapse that might throw Greece out of the euro zone. Athens consented to a framework of bailout plan with other European Union partners to swap for its rigid reforms and budget policies, Reuters added.