Rising mergers and acquisitions activity this year has been a godsend for the shares of traffic safety systems developer Redflex Holdings , and it looks like potential buyers are lining up. News that investment bank Macquarie Group had approached to buy the company for $2.50 a share in June has helped breathe life into Redflex shares, lifting them as much as 60 per cent, from close to six-year lows of $1.50 to close yesterday at $2.56. But Macquarie might have a fight on its hands given Redflex thinks it’s worth more than $2.50. Redflex announced on Friday that it will test potential third party interest in the company. “The board has decided to progress discussions with a shortlist of parties that have made indicative, non-binding interest in excess of $2.50 per share," Redflex said.