Ten percent of top ten million websites now have a certificate from Comodo, according to W³Techs.
The page says “This is 10.0% of all websites.”, but the Technologies Overview specifies: “We include only the top 10 million websites […] We use website popularity rankings provided by Alexa”.
There are now five CAs whose usage is more than one percent:
I find usage more interesting than market share. For a user, what matters is that None and Invalid Domain are going down, and the total usage is going up. Invalid Domain began to go down faster in November, when Comodo’s usage began to go up faster. I guess hosting providers play a role there.
Not only the quantity of TLS is going up, but also the quality. Support for TLS 1.2 (minimum requirement for AEAD) increases every month: https://www.trustworthyinternet.org/ssl-pulse/ And TLS 1.3 is almost done (already being used).
Not that surprising, well marketed by word-of-mouth, supported by EFF, FREE and automated (not sure to which extent, haven’t used it) If there’s no need for anything fancier than a DV cert then I think Let’s Encrypt is a natural choice for many.
Sixteen percent now (market share in parenthesis):
Comodo: 16,0% (39,7%)
IdenTrust (Let’s Encrypt): 11,9% (29,7%)
Symantec Group: 5,5% (13,7%)
GoDaddy Group: 3,0% (7,6%)
GlobalSign: 1,8% (4,5%)
DigiCert: 0,9% (2,2%)
BTW, Symantec is selling its “Website Security and related PKI solutions” to DigiCert. “The transaction, which has been unanimously approved by the Symantec Board of Directors, is expected to be completed in the third quarter of fiscal 2018, subject to the satisfaction of customary closing conditions.”