Standard & Poor's Ratings Services on Tuesday cut its outlook on Citigroup Inc to "negative" from "stable," saying the US government appears increasingly likely to leave bond holders hanging in case of another bailout of financial companies. The negative outlook signals the possibility of a future downgrade. However, S&P affirmed Citigroup's investment-grade counterparty credit and debt ratings, and said the bank's position as a stand-alone company has improved. S&P's counterparty credit and debt ratings on Citigroup now stand at A and A-1 respectively.