Retail investor Enzo Lee was watching his stock portfolio yesterday morning when he noticed that the tickers stopped moving.
He thought his screen had frozen up but when he called his stockbroker, he found out that trading on the whole Singapore Exchange (SGX) had been suspended.
"Luckily I had not opened any positions yet, otherwise I would be fuming mad now," said Mr Lee, who occasionally does intra-day trading.
At 11.38am yesterday, the SGX said it had suspended trading because of "duplicate trade confirmation messages being generated".
Trading did not resume for the rest of the day - a disruption that lasted nearly 51/2 hours. This upset traders, investors and remisiers alike.
One remisier, who wanted to be known only as H.L. Teo, said many of his clients called up demanding to know why they could not trade.
"Some even had positions open on short trades and they could not cover their positions in time. They may have even lost money. How is the SGX going to fix this?"
What makes the problem worse is that this is the third incident in less than two years, said Ms Melinda Sam, chief executive of the Securities Association of Singapore, which represents the major stockbroking firms here.
The SGX last suffered major trading disruptions in 2014.
On Nov 5 that year, multiple power supply issues led to a three-hour trading crash that affected the derivatives trading system as well.
On Dec 3 the same year, the market opening was pushed back to 12.30pm because of a software glitch.
"My members are disappointed because we thought the major problems had been fixed. We just hope this will be rectified and trading can resume the next day," said Ms Sam.
It is not uncommon for stock exchanges to go down, but most of the disruptions get fixed quickly, said CMC Markets Singapore market analyst Margaret Yang.
She said her firm also received several calls from clients asking why trading had stopped and why it did not resume.
She added: "I think this will hit the exchange's reputation. It's going to give some pause to big firms that may have been looking to list here.
"But hopefully, the pressure from brokers and traders will pressure the SGX to fix the system as soon as possible."
But Mr Andrew Hartley, managing director of broker firm CLSA Singapore, was less critical.
"It's very difficult for the market to function - even for 15 minutes - if traders cannot reconcile their orders with what is actually executed. So I think it's the right decision to keep the market closed until the issue is solved," he said.
"Obviously it's disappointing, but technical issues can happen to any exchange in the world. We should not be overly emotional about this."
For fund manager Brian Tan, who manages $30 million at Pilgrim Partners Asia, the only consolation is that the trading halt did not come on a day when there were big market moves.
"Markets were muted today. Fortunately it was not Brexit, otherwise there would really be chaos," he said.
This article was first published on July 15, 2016.
Get a copy of The Straits Times or go to straitstimes.com for more stories.