June 14, 2010, 3:44 p.m. EDT Credit spreads jump as investors seek safety May's market turmoil blows out spreads of high-yield and investment-grade debt By April H. Lee, MarketWatch NEW YORK (MarketWatch) -- Spreads between high-yield and investment-grade debt hit six-month highs last week as money fled to the safe haven of Treasury bonds -- just as it seemed investors were growing comfortable with riskier debt. Ianthe Jeanne Dugan suggests there are warning signs in the $2.8 trillion municipal-bond market, as numerous municipalities continue to struggle financially, but investors are not paying heed.