With 61 seconds in a minute, markets brace for trouble

From Amazon to airlines, companies around the world are preparing for time to stand still June 30.

The leap second, which has been implemented 25 times since 1972 to account for the slowing of the Earth’s rotation, will be the first during trading hours since markets went electronic, according to Bloomberg Business.

Ten percent of large-scale computer networks and some websites are expected to experience minor glitches due to the added second, such as those that occurred for Qantas Airways Ltd. and Reddit Inc. during the last leap second in 2012.

To compensate, computer clocks can either be stopped for one second, clocks can tick backward one second, or the extra second can be spread proportionately across the day, the latter method being favored by Google Inc. and Amazon.com Inc.

Because the leap second is scheduled for 8 p.m. EST, when markets in Asia are opening, U.S. stock markets are ending some after-hours trading early while other global markets are recalibrating their clocks ahead of time.

Read more from Bloomberg Business.