Microsoft Outlook went dark for traders just as a volatile week in markets was coming to an end, forcing many back onto phones and alternative channels. As swings in AI stocks and bonds kept traders on edge, Rita Elkazzi, the UBS Group AG execution-sales head for Australia and New Zealand, said the disruption had been a bit of a disaster and she could not believe it was still unresolved. Speaking from Sydney, she said it meant far more diligence was needed to ensure trade recaps were accurate.

The disruption is among the most severe Microsoft Corp. has suffered in recent memory. The company was still struggling to restore access to some flagship software hours after the outage began, affecting its Outlook, Teams and Copilot systems. The difficulties in communicating efficiently hindered workflows on trading desks, delayed corporate disclosure and affected email access for Japan's Ministry of Finance, which said it could not receive emails. In Singapore, traders reported some banks were unable to complete financing deals.S1S2

Elsewhere, a few Indian brokerages sent alerts about the potential impact on their services, with IIFL Capital Services warning clients of possible delays in responding to emailed queries. Australia's main exchange operator ASX Ltd. told customers it was aware of an issue affecting some Microsoft 365 services including email, but said its services remained available for normal operation. US truck and bus maker Workhorse Group Inc. said it would postpone its earnings release.S1S2

Calvin Yeoh, a portfolio manager at hedge fund Blue Edge Advisors, said he could not check emails and was struggling to access brokerage reports and some trading platforms that require email authentication. He described Outlook as the appendix of the modern financial operations world. At CMC Markets Singapore, sales trader Eugene Koh said everyone was back on the phone and WhatsApp chats were busier than usual, with tasks that normally take a second on email now requiring a call and several minutes. Ryutaro Kimura, a Tokyo-based senior bond strategist at BNP Paribas Asset Management, said trading itself was largely unaffected, but confirmations backed up, creating settlement headaches for back offices, and desks were still trading by phone and fax.S1S2

The outage drew about 200,000 reports of user issues across Microsoft services on Downdetector, ranking among the company's most severe disruptions.S1S2