SEOUL, Jan 24 (Reuters) - Round-up of South Korean financial markets: ** South Korean shares retreated on Monday and were set for their biggest daily fall in five weeks, as investors weighed concerns about U.S. Federal Reserve tightening monetary policy. The Korean won held steady, while the benchmark bond yield rose. ** The benchmark KOSPI (.KS11) fell 46.90 points, or 1.65%, to 2,787.39 as of 02:42 GMT. ** Among the heavyweights, technology giant Samsung Electronics (005930.KS) fell 0.66% and peer SK Hynix (000660.KS) fell 0.42%, while LG Chem (051910.KS) fell 3.31% and Naver (035420.KS) fell 0.90%. ** Concerns about tightening of U.S. monetary policies will keep traders nervous until there is some certainty about how far the interest rates can reach, said Lee Won, an analyst at Bookook Securities. ** Foreigners were net sellers of 323.3 billion won ($270.92 million) worth of shares on the main board. ** The won was quoted at 1,194.0 per dollar on the onshore settlement platform , steady from its previous close at 1,194.0. ** In offshore trading, the won was quoted at 1,193.1 per dollar, down 0.0% from the previous day, while in non-deliverable forward trading its one-month contract was quoted at 1,193.8. ** The KOSPI has fallen 6.39% so far this year, but lost 6.4% in the previous 30 trading sessions. ** The trading volume during the session in the KOSPI index (.KS11) was 301.39 million shares. Of the total traded issues of 930, the number of advancing shares was 81. ** The won has lost 0.4% against the dollar so far this year. ** In money and debt markets, March futures on three-year treasury bonds rose 0.04 points to 108.14. ** The most liquid 3-year Korean treasury bond yield rose by 0.4 basis points to 2.136%, while the benchmark 10-year yield rose by 0.8 basis points to 2.548%. ($1 = 1,193.3600 won)