I tend to see negative correlation between shares on any social media platform x and any social media platform y. The audiences just differ so much that anythin

I tend to see negative correlation between shares on any social media platform x and any social media platform y. The audiences just differ so much that anything that'll grab the Twitter crowd will tend to put off the StumbleUpon crowd, and so on. There's some crossover between a very few platforms, e.g. posts which get a lot of InShares will also likely get Tweeted a lot. It's quite rare, though, in my experience.