The decrease in liquidity was most obvious for the markets directly related to the core of the current turmoil, namely the market for sub-prime mortgage-backed securities (MBSs). However, since the start of the turmoil problems of illiquidity have spread further, affecting other asset-backed securities (ABSs), asset-backed commercial paper (ABCP), and basically all structured credit instruments, such as collateralised debt obligations (CDOs).
Also the liquidity in the secured non-government repurchase agreement (repo) markets was heavily impacted, as many banks no longer wanted to accept the types of securities mentioned above (MBSs, ABSs at large, and CDOs) as underlying collateral in repo transactions.