South Korean shares marked a marginal decline on Thursday, as investors kept a close eye on President-elect Donald Trump's possible trade tariffs and weighed US inflation data for October.

China's introduction of tax incentives on Wednesday to boost its troubled property market also appeared to have little effect on investor sentiment. The incentives aim to stimulate home and land sales, and ease financial pressures on developers.

The Korea Composite Stock Price Index, or Kospi, was slightly down by 0.18 points, or 0.01%, to close at 2,416.9. The Kosdaq also decreased by 7.62 points, or 1.1%, to 682.03.

US inflation rose to 2.6% year-on-year last month, marking a slight increase from 2.4% in September when the Federal Reserve started cutting rates in response to cooling prices and a weaker labor market.

The US central bank's efforts to control inflation to a 2% target could face challenges in the months ahead, as certain sectors, such as housing and insurance, continue to see high prices, impacting consumer spending and economic stability.

In economic news, South Korea's Ministry of Trade, Industry and Energy (MOTIE) and Indonesia's Ministry discussed energy strategies and investment support during the 15th Korea-Indonesia Energy Forum in Seoul on Wednesday, the trade ministry said in a same-day release.

MOTIE proposed renewing a critical minerals memorandum of understanding and requested stable liquefied natural gas supplies for South Korean firms in Indonesia.

The two countries also discussed advancing their small modular reactor (SMR) partnership, first proposed by Indonesia's president. An additional investment session facilitated direct business engagement.

In corporate news, Kia (KRX:000270) signed a memorandum of understanding with DHL Korea to develop sustainable logistics solutions using its platform beyond vehicle models, the South Korean automaker said Thursday.

The collaboration will begin with Kia's PV5 model in 2026 and will expand to the PV7 in 2027, which is customized to meet DHL's specific logistics needs, Kia said.

The South Korean company will also provide vehicle charging and warranty services as part of DHL's electrification goal while exploring expansion into Asian and European markets, according to the release.

Shares of Kia rose nearly 2% at market close.

In other news, Doosan Enerbility (KRX:034020) signed a contract with Korea Electric Power Corporation subsidiary (KRX:015760) Korea Southern Power to replace eight gas turbine casings at the Shinincheon Combined Cycle Power Plant.

The South Korean heavy industrial company will oversee the full casing replacement process for this project, using local expertise across all stages--from design and material production to installation--with support from 13 local small and medium-sized partners.

Shares of Doosan Enerbility rose more than 7% at market close on Thursday.