About 40,000 Samsung Electronics workers rallied on Thursday, demanding a larger share of the company's booming profits.
The unions want Samsung to remove the cap on bonus pay, currently set at 50% of the annual base salary.
Workers claim that a chip division employee earning 76 million won ($51,000) would receive a 2025 bonus of 38 million won ($26,000), less than a third of what a worker in a similar role at rival company SK Hynix would receive.
Samsung has rejected union demands to remove the bonus cap but says it will offer additional funding so memory division workers earn more than competitors this year.
If talks fail, unions plan an 18-day strike starting May 21, which could cost the company over 1 trillion won ($700 million) per day.