The lawsuit stems from losses the pension fund suffered after the housing market collapsed and formerly AAA-rated securities that were backed by pools of residential mortgages defaulted, the newspaper reported.

The California Public Employees Retirement System, or Calpers, the largest pension fund in the United States, brought the lawsuit against S&P in 2009. (http://on.wsj.com/1EBMpVs)

The settlement, which is expected to be announced Tuesday, was negotiated over the weekend, the report said.

Calpers also named Fitch Ratings and Moody's Investors Service in the lawsuit. Fitch previously settled, though the pension fund will continue to pursue Moody's, the Journal reported.

A Calpers spokesperson said, "We're waiting for formal announcement." Reuters could not immediately reach S&P for comment.

Separately, S&P on Tuesday is expected to announce a settlement of more than $1.37 billion with the Justice Department to settle claims it relaxed standards to win business in the buildup to the financial crisis, the Journal reported. (http://on.wsj.com/1D7CipK)

S&P, a unit of McGraw Hill Financial Inc, is trying to resolve lawsuits filed by the U.S. Department of Justice and more than a dozen states that accused it of inflating credit ratings to win more business from issuers.

(Reporting by Supriya Kurane in Bengaluru and Robin Respaut in San Francisco; Editing by Gopakumar Warrier)