On June 17th various tracking tools across the
web reported their suspicion of a Google update.
Several sources reported about the update, e.g.:
Leading speculations regarding these sudden fluctuations
- The sudden changes are
related to Wikipedia's transition to the HTTPS protocol a few days prior,
rather than being a Google update. This is the leading theory.
- A number of sources
estimate that an update affecting and boosting news websites have occurred.
According to MOZ's analysis (https://moz.com/blog/the-colossus-update-waking-the-giant)
this is a result of Wikipedia's transition to HTTPS and not an update.