JPMorgan Chase & Co.’s $13 billion fraud settlement with the U.S. government should be blocked until a court is able to review it, a Wall Street watchdog group founded by an Atlanta hedge fund manager said, Bloomberg News reported yesterday. Better Markets Inc. is seeking judicial scrutiny of the accord because it’s the largest settlement “with a single entity in the 237-year history of the U.S.,” according to a complaint filed yesterday in Washington, D.C., federal court. “No one has any ability to determine if the $13 billion agreement is fair” or “if it is a sweetheart deal,” the group said in the filing. The accord, announced in November, settled allegations that the biggest U.S. lender by assets misled investors and the public when it sold bonds backed by faulty residential mortgages. U.S. and state officials blamed JPMorgan’s actions for helping to cause the credit crisis, and said the agreement didn’t shield JPMorgan or its employees from possible charges.