* KOSPI falls, foreigners net sellers * Korean won weakens against U.S. dollar * South Korea benchmark bond yield rises SEOUL, May 27 (Reuters) - Round-up of South Korean financial markets: ** South Korean shares dropped the most in two weeks on Thursday, dragged down by tech heavyweights and on fears that central banks were closer to considering winding back their emergency stimulus. The won weakened, while the benchmark bond yield rose. ** The benchmark KOSPI fell 19.41 points, or 0.61%, to 3,149.02 as of 0217 GMT, set for its sharpest decline since May 13. ** Battery maker LG Chem tumbled near 5%, following a 6.73% drop on Wednesday, as its unit LG Energy Solution said it would be voluntarily recalling its Energy Storage System (ESS) batteries which is expected to cost the company around 400 billion won ($358.21 million). ** Among other heavyweights, chip giant Samsung Electronics fell 0.63%, while internet giant Naver and Hyundai Motor dropped 2.34% and 1.12%, respectively. ** Foreigners were net sellers of 230.3 billion won ($206.05 million) worth of shares on the main board. ** South Korea's central bank kept monetary policy unchanged on Thursday but upgraded its economic outlook as exports and inflation perked up, shifting the focus to the prospects of an end to current accommodative settings. ** "As the recent weight rebalancing in MSCI takes effect, shares in South Korea, Japan and Taiwan, which weightings have been reduced, are falling together," said Shinhan Investment Corp analyst Choi Yoo-june. ** The won was quoted at 1,118.6 per dollar on the onshore settlement platform , 0.15% lower than its previous close at 1,116.9. ** In offshore trading, the won was quoted at 1,117.8, while in non-deliverable forward trading its one-month contract was quoted at 1,117.1. ** In money and debt markets, June futures on three-year treasury bonds rose 0.03 points to 110.90. ** The benchmark 10-year yield rose by 2.7 basis points to 2.154%. ($1 = 1,117.6800 won) (Reporting by Joori Roh; Additional reporting by Jihoon Lee; Editing by Rashmi Aich)