A Team of US researchers at UC Berkeley conducted a study on the HTTPS traffic analysis of ten widely used HTTPS-secured Web sites with surprising results. Berkeley researchers have revealed a technique for identifying individual web pages visited by users, with up to 89% accuracy. The list of website using HTTPS examined includes Mayo Clinic, Planned Parenthood, Kaiser Permanente for health-care industry, Wells Fargo, Bank of America for banking and also Net ix and YouTube for streaming video. Be aware this means that an ISPs for example could be able to spy on web browsing even if it is on a secure channel via HTTPS.”]
Source: https://securityaffairs.co/wordpress/22830/hacking/https-traffic-analysis.html