I was all excited, I saw widespread reports of a Bing Search algorithm update at WebmasterWorld and then I dug deeper and it seems it was more related to how Google Analytics reports organic traffic from Bing.

Something changed because of several really large sites I track, I saw as much as a 25% decrease in organic traffic this past week to the week before. But at the same, I saw a 200%+ increase in referral traffic from Bing.

Here are some of the larger sites, but I checked way more than just four site profiles:

Organic Bing Traffic Down 20% But Bing Referral Traffic Up 350%
Organic Bing Traffic Down 5% But Bing Referral Traffic Up 145%
Organic Bing Traffic Down 10% But Bing Referral Traffic Up 265%
Organic Bing Traffic Down 22% But Bing Referral Traffic Up 230%

Shepard from WebmasterWorld first spotted this and said:

Interesting, maybe Bing changed their URL structure or maybe this has to do with the Bing HTTPS change.

Forum discussion at WebmasterWorld.