Binance.US and Coinbase (COIN) are on a list of crypto companies questioned this week by the chairman of the U.S. Senate Finance Committee about how they protect the investors using their services in light of the widespread damage caused by the fall of FTX.

Sen. Ron Wyden (D-Ore.) sent letters to six CEOs of prominent cryptocurrency firms – including Bitfinex, Gemini, Kraken and KuCoin – asking them to explain their structures, whether they separate customers’ assets from their own and how they guard against market manipulation and internal conflicts of interest.

The letters – dated Nov. 28 – request balance-sheet information and explanations for the companies’ reserves, including whether they’re audited.