Goldman Sachs Group Inc. must face fraud claims brought by ACA Financial Guaranty Corp. over a mortgage-based investment that led to a settlement with the U.S. Securities and Exchange Commission. ACA Financial sued Goldman Sachs in New York State Supreme Court in January 2011, accusing the company of fraudulent inducement, fraudulent concealment and unjust enrichment in connection with a collateralized debt obligation known as Abacus.