These disruptions have major consequences for any business that relies on telecom for delivering their services, including, banking, trading, call centers, remotely managed services etc. This event also underlines the necessity for redundancy and why policymakers and regulators must liberalize international gateways to allow a number of different submarine cables connecting different destinations to land in a country.
From Bloomberg:

Damaged cables include the APCN2 cable and Sea-Me-We3 cables, Chunghwa’s Leng said. Eight STM-1 cables from Okinawa off Japan and 4 STM-1 cables to Shanghai are acting as backup, Chunghwa said in a statement. The company may also use the ST-1 satellite.
Singapore Telecom, France Telecom SA and Pakistan Telecommunication Co. are among companies that own the Sea-Me-We3 cables linking Europe to Asia. Operators in the APCN2 cable network that connects Japan, Korea, China, Taiwan, Hong Kong, Philippines, Malaysia and Singapore include China Unicom Ltd., StarHub Ltd., Telekom Malaysia Bhd. and Telstra Corp.
[..]“The repairs could take two to three weeks,” said Leng Tai-feng, president of Chunghwa Telecom Co.’s international business. The Taipei-based company, Taiwan’s largest phone operator, said two of its undersea cables were cut.
HSBC Holdings Plc said its online banking services were down, while Chunghwa said almost no calls could be made to Southeast Asia, causing disruption to companies including First State Investments in Singapore.
“I can’t trade if I don’t know the prices,” said David Leong, who heads the Singapore trading desk at First State, which manages $15 billion in equities in Asia and emerging markets. “I’ve put in limit orders to try to minimize the damage, but even then you need to have the basic information.”