(100)Institutions should hold a diversified buffer of liquid assets that they can use to cover liquidity needs in a short term liquidity stress. As it is not possible to know ex ante with certainty which specific assets within each asset class might be subject to shocks ex post, it is appropriate to promote a diversified and high-quality liquidity buffer consisting of different asset categories. A concentration of assets and overreliance on market liquidity creates systemic risk to the financial sector and should be avoided. A broad set of quality assets should therefore be taken into consideration during an initial observation period which will be used for the development of a definition of a liquidity coverage requirement. When making a uniform definition of liquid assets at least government bonds, and covered bonds traded on transparent markets with an ongoing turnover would be expected to be considered assets of extremely high liquidity and credit quality. It would also be appropriate that assets corresponding to Article 416(1)(a) to (c) should be included in the buffer without limitations. When institutions use the liquidity stock, they should put in place a plan to restore their holdings of liquid assets and competent authorities should ensure the adequacy of the plan and its implementation.