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In March, my team in Shanghai launched a site redesign of our English language website (targeted at expats in China) which: Changed the URL's to be more SEO friendly (keyword based, shorter, etc) Implemented endless scrolling to replace previous pagination Changed some front end layouts Changed page title and meta description tags to use keywords, be unique, use correct lengths Since then, we see in Google Analytics, traffic form Google organic branded search terms has been steadily dropping (between 5 - 20% depending on the term). Not provided is down 2%. We do not rank for many non-branded terms, so have no statistical significance there. However in Google Webmaster Tools, impressions of branded queries are also down, along with non-branded search terms (including those we tried to optimise for). We see similar traffic drops from other search engines as well (Bing, Baidu) but not at as high a level (only 3% or so). We have not changed any other marketing strategy online or offline. We have tested / done: 1. Changing title tags 2. Reverting to old pagination (as we say in GWT a drop in indexed pages) 3. Checked the tracking code is working 4. Checked our rankings (we still rank position 1 for our branded queries and even some non branded) 5. Submitted new XML site map The only large issue we could find is that from that day there were over 300,000 page not found 404 errors (which we are now redirecting by 301s as Google shows them to us, and have been doing so for 2 weeks). Nothing is helping us so far, organic traffic continues to drop week on week, so I am reaching out to the Moz community. Can anybody think of a reason for such a dramatic drop? Please help!