Four out of five companies and municipalities in Japan face a deadline of sorts Wednesday, the day Microsoft Corp. ends technical support for older versions of its Internet Explorer (IE) browser. About 30 percent of them use versions that may now be at risk.

Although the application will continue to work, Microsoft will no longer release security updates for older versions to guard against hackers.

The company estimates that 80 percent of firms and local government offices use the program. Microsoft Japan spokesman Masanori Kanazawa said about one in three of the total use older versions of IE.