It's said the theoretical aim of the ECB Two-tier systemECB Two-tier system (exempt a portion of the excess reserves from negative rates) was designed to:
offset the direct costs of negative interest rates on banks, thereby helping to sustain the pass-through of low policy rates to bank lending rates
push banks to trade/lend their excess liquidity in the money markets.
I get point one, but struggling with 2), can you help out?