Looking at the last 24 hours or so of all retweets on Twitter, it appears Donald Trump is the most retweeted account from this time sample:
1. realDonaldTrump 476,732
2. BTS_twt 454,050
3. bts_bighit 316,856
4. superm 236,266
5. Stranger_Things 194,654
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Now granted, I don't know how many tweets the other accounts made, but I suspect the retweets per original tweet average would push Trump down. In other words, he has a lot of retweets because he makes a lot of tweets.
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Now check how many of Trump’s retweets come from real accounts vs bots. It won’t be a contest if you require actual people to amplify the content.