NEW YORK (AP) ¿ Fitch Ratings boosted some ratings of State Street Corp. on Tuesday, as the financial services provider has worked to improve its capital and bolster its liquidity. The ratings agency said its actions were not impacted by the Boston company's announcement earlier in the day that it would buy the securities services business of Italian banking group Intesa Sanpaolo for about $1.87 billion in cash. State Street said the acquisition would help expand its presence overseas, as the Intesa unit has offices in Italy and Luxembourg. The deal is expected to close in the second quarter. Fitch Ratings raised the individual and preferred stock ratings of State Street and subsidiary Sate Street Bank and Trust Co. to "B/C" from "C'' and also lifted the preferred stock rating of Sate Street's trust preferred subsidiaries one notch in investment grade status to "BBB+" from "BBB." The ratings agency maintained the issuer default ratings of State Street and its subsidiaries at "A+/F1+." The company's outlook is stable. State Street had $17.9 trillion in assets under custody and administration as of Sept. 30. The custody bank has about $420 billion in alternative assets under administration. Shares of State Street gained $1.34, or 3.2 percent, to $43.60 in midday trading. Over the past year, the stock has traded in a range of $14.43 to $55.87.