The credit-rating agency also affirmed its "BB+" corporate credit and senior unsecured debt ratings for the Middlebury, Conn.-based company.
S&P said payments for antitrust litigation, restructuring activities, and debt retirement premiums have hampered Chemtura's financial progress.
"Still, management's ongoing efforts to address problem operations and commitment to strengthening the capital structure enhance prospects that credit quality metrics can improve to the level appropriate for the current ratings perhaps by the end of 2007," S&P credit analyst Wesley E. Chinn said in a statement.
The analyst highlighted Chemtura's 2005 acquisition of Great Lakes Chemical Corp., which he said added complementary product lines and strengthened Chemtura's business mix.
Chemtura shares rose 7 cents to $9.25 in morning trading on the New York Stock Exchange.
