WASHINGTON (AP) -- The U.S. government says Standard & Poor's knowingly inflated its ratings on risky mortgage investments that helped trigger the 2008 financial crisis.
The credit rating agency gave high marks to mortgage-backed securities because it wanted to earn more business from the banks that issued the investments, the Justice Department alleges in civil charges filed in federal court in Los Angeles.
The government is demanding that S&P to pay at least $5 billion in penalties.
The case is the government's first major action against one of the credit rating agencies that stamped their approval on Wall Street's soon-to-implode mortgage bundles. It marks a milestone for the Justice Department, which has long been criticized for failing to act aggressively against the companies that contributed to the crisis.
S&P, a unit of New York-based McGraw-Hill Cos., called the lawsuit "meritless."
"Claims that we deliberately kept ratings high when we knew they should be lower are simply not true," the company said in a statement.
According to the lawsuit, S&P knew that home prices were falling and that borrowers were having trouble repaying loans. Yet these realities weren't reflected in the safe ratings S&P gave to complex real-estate investments known as mortgage-backed securities and collateralized debt obligations.
At least one S&P executive who had raised concerns about the company's proposed methods for rating investments was ignored.
S&P executives expressed concern that lowering the ratings on some investments would anger the clients selling these investments and drive new business to S&P's rivals, the government claims.
"Put simply, this alleged conduct is egregious -- and it goes to the very heart of the recent financial crisis," Attorney General Eric Holder said Tuesday.
Holder called the case "an important step forward in our ongoing efforts to investigate and punish the conduct that is believed to have contributed to the worst economic crisis in recent history."