The NFL's $765 million settlement of concussion claims has been preliminarily rejected by a federal judge due to fears that the sum may not be enough to cover injured players.

U.S. District Judge Anita Brody has asked for more financial details from the parties.

Brody notes the plan is designed to cover nearly 20,000 men for 65 years. She says she is mostly concerned that not all retired players who are someday diagnosed with related brain injuries will be paid.