SEOUL, Feb 1 (Reuters) - South Korea's SK Hynix Inc posted a quarterly operating loss on Wednesday as memory chip prices plunged due to a deepening downturn in global tech demand.

The world's second-biggest memory chipmaker reported a 1.7 trillion won ($1.38 billion) operating loss in the October-December quarter, from 4.2 trillion won profit a year earlier.

This compares with expectations for a 1.3 trillion won operating loss according to 21 analysts compiled by Refinitiv SmartEstimate, which is weighted toward analysts that are more consistently accurate. ($1 = 1,232.4700 won) (Reporting by Joyce Lee Editing by Chris Reese)