GLOBAL MARKETS-Stocks, bond yields slip as Ukraine crisis deepens

* S&P 500 index sinks below 2,000 after record Wednesday close * Euro hits 21-month low vs Swiss franc, weaker against yen * Traders focus on weak European data, brush off upbeat U.S. GDP * Bund yields hit new lows, U.S. 30-year yield lowest in 14 months (Updates market action, adds quote) By Richard Leong NEW YORK, Aug 28 (Reuters) - Stock markets around the world fell on Thursday after Ukraine said Russia had moved more troops into the country, deepening the regional cris