Employees wait for the elevators at Samsung Electronics' building in Seoul in this July 22 photo. Yonhap

According to the corporate tracker Leaders Index, the proportion of employees in their 20s at major Korean conglomerates decreased to 21.6 percent in 2023 from 23.4 percent in 2021, while the share of workers aged 50 or older increased to 22 percent from 20.8 percent.

During the period, Samsung Electronics, LG Display, Samsung Electro-Mechanics and SK hynix showed the sharpest declines in the number of employees aged under 30, it explained.

The corporate tracker revealed the findings after analyzing the sustainable management reports of 123 companies — among Korea's 500 largest firms by revenue — which detailed employee age groups over the past three years.

According to the analysis carried out, the number of Samsung Electronics' employees aged under 30 dropped to 72,525 in 2023 from 89,897 in 2021.

The tech giant has not disclosed the number of its workers aged 50 or older.

However, its sustainable management report showed that the number of its employees aged 40 or older has increased to 81,461 from 68,288 during the same period.

The number of LG Display's employees aged under 30 fell to 28,493 from 34,929 during the period, while the number of its workers aged 50 or older rose to 1,461 from 1,061.

The number of Samsung Electro-Mechanics' employees aged under 30 decreased to 13,932 from 18,048. The subsidiary of Samsung Electronics has not disclosed the number of its workers aged 50 or older, just like its parent firm.

The number of SK hynix's employees aged under 30 fell to 9,833 from 11,934, while the number of its workers aged 50 or older increased to 2,921 from 1,815.

In contrast, carmakers, shipbuilders, steelmakers, construction firms and machinery manufacturers, which have relied heavily on skilled older workers, showed an increase in the proportion of their workers in their 20s.

However, the proportion of their employees in their 50s remained high.

Although the number of Kia's employees aged under 30 rose to 2,539 in 2023 from 1,017 in 2021, the proportion of its workers aged 50 or older reached 55.4 percent last year, nearly eight times higher than the proportion of the carmaker's employees aged under 30.

"These results can be attributed to the tendency of Korean firms looking for skilled workers instead of new employees and to their sluggish expansion to new businesses, amid demographic changes caused by the low birthrate and aging population," a Leaders Index official said.