[everfree]

For better or worse, Coinbase does not have a USDC/USD trading pair, or USDC trading pairs with most cryptos (BTC, ETH, etc.). For the most part they have USD trading pairs, which if you have USDC you're typically expected to access by redeeming your USDC for USD and then using the USD trading pairs. But since USDC to USD redemption is halted for now, you effectively cannot trade USDC for most common cryptocurrencies on Coinbase without going through one of their (afaik) three live USDC trading pairs - USDC/EUR, USDC/GBP, and USDT/USDC.

However, other exchanges actually do have USDC markets for most other cryptocurrencies. If you deposit your USDC with them, then you can directly trade order books on USDC/USD, BTC/USDC, and ETH/USDC, which function regardless of the lack of redemption and regardless of the actual market price of USDC.

If Coinbase had lots of USDC trading pairs like other exchanges do, it would avoid the issue you outlined in your comment, but it would also fragment liquidity across two markets that are effectively identical during business-as-usual periods where redemptions function properly.

[danielvf]

That's not true, Coinbase has active USDC/USDT, USDC/EUR, and USDC/GBP pairs. I've traded on them overnight. They just disabled the 1-1 conversion with USD.

[everfree]

My bad. Looks like they added those pairs in 2021 and I didn't notice (though it looks like you have to "opt out of the USD and USDC unified experience" in order to access them). I edited my comment accordingly.