South Korean shares closed higher for a second day on Wednesday, lifted by buybacks at SK Hynix (KRX:000660) and Samsung Electronics (KRX:005930) and firmer external sentiment as investors awaited Nvidia's earnings.

The Korea Composite Stock Price Index, or Kospi, increased by 65.47 points, or 0.97%, to close at 6,808.21. The Kosdaq, however, fell by 0.28 points, or 0.03%, to close at 826.87..

Shares of SK Hynix and Samsung Electronics added nearly 1% and 2% at market close.

In economic news, the Composite Business Survey Index (CBSI) for South Korean enterprises increased by 1.1 points to 99.6 in August, according to data from the Bank of Korea on Wednesday.

A print above 100 indicates optimism, while a reading below suggests negative sentiment. The latest reading compared with 98.5 points recorded in the previous month.

Within the manufacturing sector, the index edged up 0.6 points to 103.8, while the index for the non-manufacturing sector rose 1.5 points to 96.7. Meanwhile, the Economic Sentiment Index, which combines the CBSI and the Consumer Survey Index (CSI), rose 1.5 points to 99.4.

In corporate news, Development Advance Solution (KRX:058730) was named preferred bidder for EPC and O&M contracts for the Sinan Mitra 1 & 2 and Horus solar projects, with value to equal at least 5% of latest revenue of 273.2 billion won. Shares surged over 9% at the close.