...DALLAS (S&P Global Ratings) Jan. 18, 2018--S&P Global Ratings has revised its outlook to stable from negative and affirmed its '##' long-term and underlying ratings on the City of Houston, Texas' general obligation (GO) bonds. "The outlook revision reflects our view that recent changes to Houston's pension plans are likely to have a positive effect on the city's ability to address the unfunded liability," said S&P Global Ratings credit analyst Andy Hobbs. Houston's ad valorem tax pledge, within the limits prescribed by law, secures the GO bonds. Despite a revenue tax cap that limits the city's ad valorem tax growth, we did not make a rating distinction for the limited-tax GO pledge due to the city's stable and very strong liquidity, which provides it financial flexibility to manage any unforeseen challenge. The '##' rating reflects our opinion of the city's: + Strong economy; + Very strong management; + Adequate budgetary performance; + Adequate budgetary flexibility; + Very strong liquidity;...