$USDC $FDUSD USDC and USDT are the two most popular stablecoins, pegged to the USD at a 1:1 ratio. USDC (USD Coin) is issued by Circle, and is more transparent with regular audit reports, with assets primarily backed by cash and U.S. government bonds. USDT (Tether) is issued by Tether Limited, has a larger trading volume but has faced controversies regarding transparency and asset reserves. Both are widely used in cryptocurrency trading, but USDC is often considered more reliable and transparent.