SEOUL, Aug 19 (Reuters) - Round-up of South Korean financial markets: ** South Korean shares fell on Tuesday amid a number of uncertainties related to U.S. President Donald Trump's talks with Russia and Ukraine regarding peace resolutions, and ahead of Federal Reserve's annual Economic Policy Symposium in Jackson Hole. The won weakened, while the benchmark bond yield rose. ** The equity benchmark KOSPI .KS11 was down 10.78 points, or 0.34%, at 3,166.50 as of 01:53 GMT. ** Among index heavyweights, chipmaker Samsung Electronics 005930.KS rose 0.29%, while peer SK Hynix 000660.KS lost 0.56%. Battery maker LG Energy Solution 373220.KS slid 0.52%.
** U.S. President Donald Trump told Ukraine President Volodymyr Zelenskiy on Monday that the United States would help guarantee Ukraine's security in any deal to end Russia's war there, though the extent of any assistance was not immediately clear.
** Fed Chair Jerome Powell speaks on Friday at the central bank's annual Wyoming research conference. ** Hyundai Motor 005380.KS and sister automaker Kia Corp 000270.KS were up 0.46% and up 0.98%, respectively. Steelmaker POSCO Holdings 005490.KS shed 0.33%, while drugmaker Samsung BioLogics 207940.KS fell 0.19%. ** Of the total 930 traded issues, 254 shares advanced, while 614 declined. ** Foreigners were net sellers of shares worth 225.6 billion won. ** The won was quoted at 1,389.9 per dollar on the onshore settlement platform KRW=KFTC, 0.13% lower than its previous close at 1,388.1. ** In offshore trading, the won KRW= was quoted at 1,389.5 per dollar, down 0.1% on the day, while in non-deliverable forward trading its one-month contract KRW1MNDFOR= was quoted at 1,386.8. ** The KOSPI has risen 31.97% so far this year. ** In money and debt markets, September futures on three-year treasury bonds KTBc1 lost 0.03 point to 107.32. ** The most-liquid three-year Korean treasury bond yield KR3YT=RR rose by 0.8 basis points to 2.432%, while the benchmark 10-year yield KR10YT=RR rose by 2.6 basis points to 2.853%.