Where does Coinbase store money?

Can you please elaborate on where Coinbase actually stores the funds entrusted to them by their users? Is it in a traditional bank, or do they utilize some form of decentralized storage solution? Given the volatile nature of cryptocurrencies, I'm particularly interested in understanding the measures Coinbase has in place to ensure the safety and security of their clients' digital assets. Are there any regulations or audits that Coinbase undergoes to maintain transparency and accountability in their financial management practices?