There were speculations that Circle and Tether, which supports USDC and USDT respectively, have some connection with FTX and Alameda. However, Jeremy Allaire, Circle CEO cleared via Twitter that the firm has never given any loans to FTX or Alameda and also said that Circle has never received any FTT as collateral. Further he said that there was a small portion of equity among Circle and FTX.
On the other hand, Paolo Ardoino who is a chief technology officer at Tether was quick enough to claim that Tether is not connected with FTX or Alameda in any aspect. These comments emerged after Sam Bankman-Fried agreed to sell FTX to its competitor Binance to avoid collapse.
Source: https://coinpedia.org/crypto-live-news/circle-tether-deny-any-connection-with-ftx-or-alameda/