Actually, that is a bit of a "half-truth" in the current regulatory landscape. While MAS Notice 649 is indeed the governing notice for liquidity requirements, the 18% figure you're thinking of is a bit dated and only applies to a specific group of banks. Here is the breakdown of how the rules actually work: 1. Two Different Frameworks — Under Notice 649, banks follow one of two regimes depending on their size and systemic importance: Liquidity Coverage Ratio (LCR): This applies to internationally active banks and Domestic Systemically Important Banks (D-SIBs) (like DBS, OCBC, and UOB). They don't use a flat 18% ratio; instead, they must maintain an LCR of at least 100%.