Deposit run-off is generally considered the largest threat to a bank's liquidity because:

• Deposits represent a significant portion of a bank's funding base
• Retail deposits can be withdrawn rapidly and simultaneously by many customers
• This creates immediate cash outflow pressure
• Unlike wholesale funding, retail deposits are typically unsecured and can be withdrawn without notice
• Historical banking crises often feature deposit runs as a primary trigger

While loss of wholesale funding and secured funding are significant threats, deposit run-off typically poses the most immediate and widespread liquidity risk due to its scale and speed.