As many major publishers and platforms have transitioned to using HTTPS, a great move for user privacy and security, a side effect has been a commensurate rise in dark social traffic — traffic that can’t be attributed to a particular referrer. Luckily, sites using HTTPS can still have their outbound traffic properly attributed if they chose to do so (e.g. by use of the meta referrer tag). We’ve chronicled major changes to dark social attribution here to ensure that publishers are up to date on the meaning of their traffic sources.

One of the largest sources of dark social on the web has been the Yahoo homepage, which drives an enormous amount of traffic and moved to using HTTPS over the past year, causing their traffic to become dark for publisher sites that don’t default to HTTPS. For publishers who have partnerships with Yahoo, this has meant that directly attributing the volume of traffic they’re receiving has been difficult.

On June 2, though, Yahoo pushed a change to add a meta referrer tag to their homepage and correctly attribute their traffic to sites using HTTP, and we’ve immediately seen dramatic results, as represented in the figure below.

Since the change, we’ve seen a roughly 6x increase in attributable traffic coming from Yahoo, making it one of the most significant referrers on the web. On the day before the change, Yahoo was the 16th largest referrer across the Chartbeat network, and in the hours after the change Yahoo jumped to the sixth largest referrer (after Facebook, Google Search, Twitter, Google News, and Bing).

Between this change and other updates by LinkedIn and Facebook, we’ve seen significant moves in the past 18 months by many of the world’s largest platforms to ensure that all traffic is correctly attributed. We’ll continue to work with publishers and platforms to track down sources of dark social, and we’ll keep you updated here as more publishers move into the light.

*Technical note: for those used to the hsrd.yahoo.com referrer, traffic sent via this change will carry the referrer yahoo.com, not hsrd.yahoo.com.