Philadelphia’s general-obligation debt rating Monday was raised two steps to A+, fifth-highest, by Standard & Poor’s, after three fiscal years of surpluses.

The rating company also gave a stable outlook and credited a state oversight board called the Pennsylvania Intergovernmental Cooperation Authority with the financial condition of the nation’s fifth-most populous city.

“The stable outlook reflects our view of the city’s strong budget performance due, in part, to oversight from PICA,” Hilary Sutton, a credit analyst, said in a statement today.

Mark McDonald, a spokesman for Mayor Michael Nutter, didn’t immediately return a call and e-mail requesting comment.

Tax-exempt Philadelphia general-obligations maturing in August 2031 traded today at an average yield of 3.5 percent, or 2.84 percentage points over benchmark munis, wider than the average spread of 2.39 percentage points since June 30, data compiled by Bloomberg show.

Moody’s Investors Service grades Philadelphia a step lower at A2 and Fitch Ratings two steps lower at A-.