The Friedman memo showed they were 1-1 cash/usdt back in September, and they've stated clearly it's institutional money coming in. In fact, that's exactly what I would expect for large buyers trying to spread their purchases across exchanges who don't use USD directly.

"I agree that if no one was able to get fiat in or out of Tether and USDT were still being issued that would be a huge problem. As it stands, however, institutional customers are able to deposit USD to Tether, and this is how USDT is being issued."

https://www.reddit.com/r/BitcoinMarkets/comments/7fsfwl/dail...