The Office of Fair Trading had provisionally decided to close its investigation into alleged anti-competitive conduct in the sports retail sector.
The OFT said it expects to reach a final decision later this year.
Both Sports Direct and JJB sports have welcomed the decision.
Sports Direct chairman Keith Hellawell said: “We welcome the announcement by the OFT. It is in line with Sports Direct’s long held views on the investigation. It is also consistent with previous decisions taken by other regulatory bodies.”
JJB Sports said that “as the leniency applicant, JJB has been co-operating fully with the OFT throughout its investigation, and will continue to do so”.
It added: “JJB is not in a position to comment on the reasons behind the OFT’s provisional decision.”
The OFT and the Serious Fraud Office kicked off an investigation into the wider sports retailing market, reviewing practices that it had reason to believe may have flouted rules under the Fraud and Enterprise Acts.
Retail Week Knowledge Bank said both lines of investigation were effectively initiated by JJB’s approach to the OFT.
It was investigating potential conflicts of interest due to the practice of cross holdings between the leading multiple retailers, international suppliers and their senior managements, plus senior personnel moving between the companies.