A third financial ratings agency lowered the credit rating for the Chicago Public Schools to "junk" status on Friday, dealing another blow to the cash-strapped city school system. The move by Standard & Poor's Ratings Service followed similarly grim statements issued recently by the other two major agencies, Fitch Ratings and Moody's Investors Services. After observing "the board's decisions in constructing" a new budget for the coming fiscal year, Standard & Poor's downgraded CPS' long-term rating from "BBB" to "BB" with a negative outlook. In a statement, Standard & Poor's made references to the Chicago Board of Education's perennial deficits, dwindling cash reserves and the vote last month to borrow as much $1.16 billion by selling bonds.