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Hi etakgoz, That's a huge drop. I've actually seen a similar drop in traffic before in the past, specifically due to a site redirection issue and also Google Penguin penalties. What caused a mis-diagnosis for me in the past was that our site redirection happened at almost the same time as Google core algorithm changes during the same period. Have you taken a look at the algorithm change timelines to see if it's possibly an external factor that caused the drop in traffic? Other than that, did you have any tracking tools or software similar to Moz that you were using to keep track of site issues or the backlink profile? The decrease in traffic is pretty severe and there could be a multitude of issues possibly causing this. Was there a similar decrease in search rankings along the same period of time as well? Sorry for the questions, but it'll really help if you could provide more details for further diagnosis.