MAS Notice 649 does not specifically require banks in Singapore to maintain a minimum liquid asset ratio of 18%. Instead, MAS Notice 649 pertains to the liquidity coverage ratio (LCR) requirements for banks. The LCR is designed to ensure that banks have an adequate stock of unencumbered high-quality liquid assets (HQLA) that can be converted into cash to meet their liquidity needs for a 30-day stress scenario. The specific LCR requirements can vary depending on the type of bank and its systemic importance. For example, domestic systemically important banks (D-SIBs) in Singapore are typically required to maintain an LCR of at least 100%. Other banks may have different requirements based on their size, complexity, and risk profile. For the most accurate and up-to-date information, it is advisable to refer directly to the Monetary Authority of Singapore (MAS) or consult the latest version of MAS Notice 649.