NEW YORK — Samsung expects its quarterly operating profit to fall 29 percent compared with last year, adding to the tech sector’s unease about the effect of slowing global economic growth.

The announcement from the South Korean computer chip and smart phone giant comes less than a week after a weak outlook from Apple jolted markets.

Samsung said there’s weak global demand for chips amid a worldwide economic slowdown, while its smart phones are facing stronger competition. The weakening trend follows many record-breaking profit quarters from Samsung. In October, the company said there was strong demand for its memory chips, although it had previously noted the slowdown for smart phones. It has been revamping its lower-cost phone lineup.

In a rare move for Apple, meanwhile, last week the company walked back its sales expectations for the last quarter of 2018, citing flagging sales in China .

China is a huge smart phone market, accounting for one-third of the world’s handset shipments.