Standard&Poor's Ratings Services raised its short-term rating on Merrill Lynch Puttable FLOATs/RITES Trust, Series PT-1000, puttable floating option tax-exempts receipts issues to 'AAA/A-1+' from 'AAA/A-1'. This action follows Standard&Poor;s upgrade of Merrill Lynch&Co. Inc. to 'AA-/A-1+' from 'A+/A-1'.