South Korea's KOSPI climbed more than 3 percent, helped by a rebound in heavyweight semiconductor shares and buying by institutions and foreign investors. Volatility remained high, with a buy-sidecar triggered during the session in the main board market.

On July 21, the KOSPI closed up 231.68 points, or 3.56 percent, at 6,747.95. The index opened up 37.61 points, or 0.58 percent, at 6,553.88 and rose as high as the 6,800 level during the session.

As gains widened quickly around large semiconductor shares, the main board market triggered a buy-sidecar during the session. When a buy-sidecar is triggered, the effectiveness of program buy orders is suspended for 5 minutes.

In the main board market, institutions posted net buying of 1.39 trillion won, while foreigners bought a net 295.0 billion won. Individuals sold a net 1.66 trillion won.

Among the top stocks by market capitalisation, Samsung Electronics ended at 259,000 won, up 15,000 won, or 6.15 percent, from the previous session. SK Hynix rose 72,000 won, or 4.08 percent, to 1,836,000 won.

Elsewhere, SK Square gained 6.46 percent, while Samsung Electro-Mechanics added 2.75 percent, Samsung Biologics rose 3.72 percent, Samsung Life advanced 4.81 percent and KB Financial Group climbed 3.08 percent.

Hyundai Motor ended flat. LG Energy Solution fell 0.16 percent.

The Kosdaq ended up 3.70 points, or 0.49 percent, at 753.34.

In the Seoul foreign exchange market, the won ended at 1,473.50 per dollar, up 5.00 won from the previous session.

Han Ji-young (한지영), a researcher at Kiwoom Securities, said, "In terms of valuation, earnings and flows, this is a section where it is reasonable to expect a rebound after consolidating a bottom rather than further declines in the index." She added, "It is necessary to prioritise a strategy of increasing weight through staggered buying, centred on semiconductors that have recently seen excessive declines."