What is First Digital USD backed by?

Could you please clarify the underlying assets backing the First Digital USD? As I understand, FDUSD is purported to be a stablecoin pegged to the US dollar. However, unlike other stablecoins that may be collateralized by cash, securities, or even cryptocurrencies, it's crucial to know what specifically underpins the value of FDUSD. Given the recent surge in its popularity and the fact that it's issued by a Hong Kong-based company, it's natural to have questions about its trustworthiness and transparency. Could you elaborate on the assets backing FDUSD and how they ensure its stability and liquidity? This information is crucial for investors and traders alike to make informed decisions about FDUSD.