Headquarters of Hyundai Motor and Kia in Seoul / Courtesy of Hyundai Motor Group

Hyundai Motor and Kia are displaying lackluster stock performances due to sluggish auto sales and escalating concerns over global economic doldrums, according to data and analysts, Friday.

Both carmakers experienced a decline in sales in September, impacted by decreasing auto demand, especially in key markets like the United States.

According to data from the two firms, their combined auto sales in the world's largest economy fell by 10.4 percent last month compared to the same period a year earlier.

This has raised concerns about a delayed rebound in their stock prices. Hyundai Motor shares reached a high of 299,500 won ($224) per share in June but have since experienced significant volatility as the global economy enters a downturn. Additionally, the prolonged high interest rates pose a risk to revitalizing auto demand.

Kia shares have followed a similar pattern, reaching a yearly high of 135,000 won per share in June. However, the stock price has also struggled to achieve any significant rebound since then.

“Global sales at Hyundai Motor and Kia fell approximately 3 percent below earlier estimates,” said Yoon Hyuk-jin, an analyst at SK Securities.

“Their production also dropped due to strikes at their parts suppliers. The high interest-sparked demand slowdown and toughening market competition also come as a major concern to the two automakers.”

Hyundai Motor aims to enhance its profitability by diversifying its electric vehicle (EV) lineup with the global launch of the Casper EV and by boosting sales of hybrid vehicles throughout this year.

Kia also expressed hopes of offsetting the decline by increasing sales of its strategic EV3 compact SUV in Europe during the fourth quarter. Additionally, the company plans to launch its newest flagship Sportage SUV in the same period, which it anticipates will serve as a key sales driver both domestically and internationally.