WebPKI Observatory — Market Share
Five CAs control 91.8% of all trusted certificate issuance, led by Internet Security Research Group at 39.2% and Google Trust Services at 19.9%. The top three CAs hold 72.93% market share, producing an HHI of 2325 that signals moderate concentration. Despite 89 trusted CAs operating globally, 75 sit in the long tail with minimal issuance volume but full trust store inclusion.