Outline of the presentation: Look at long term trends of MTS cash liquidity (2006-2017). If, when and how liquidity changed. - Liquidity long term trends and market making: if and how the evolution of liquidity affected market making strategies. - Liquidity long term trends and large trades execution. - New regulation and market competition are currently the two main forces driving down market making profitability. A first empirical test is based on the impact of a change in the market making rules set by the Treasury.