A loud whistling noise halted trading on 7 global stock markets for several hours

Last week the Nasdaq Nordic exchange was put out of order after a fire alarm in a Swedish data centre caused a fire suppression system to trigger.
The system made such a loud noise that it shut down servers for the Nasdaq.
The whistling sound may have damaged "the alignment of disk drives’ read-write heads to the data tracks," according to Quartz.LONDON — Stock market trading in seven European countries was knocked out for several hours last week with an unusual cause of the disrupti