A once technical corner of European banking policy is suddenly commanding attention from money markets, as investors weigh what would happen if the European Central Bank decided to double the amount of cash lenders are obliged to keep on reserve. The move, known as raising the minimum reserve requirement (MRR), sounds like plumbing, but analysts at ING argue it could gradually reshape how sensitive short term funding costs are to any future shift in policy.
Why a €174bn cut is being called marginal
The starting point is the enormous cushion of spare cash sitting in the banking system. Excess liquidity across the euro area currently stands at €2.2tr. Against that backdrop, doubling the reserve requirement would, in effect, remove roughly €174bn in a single step. Set beside a €2.2tr pool, that one off reduction looks small, which is why the immediate market impact is expected to be marginal.
The more important point is direction rather than size. Draining €174bn would nudge the system closer to a threshold where funding rates begin to respond far more sharply to any change. Put differently, the buffer that keeps money market rates calm would grow a little thinner. That nervousness is already visible: market expectations for Euribor/OIS spreads edged slightly higher as soon as the headlines about a possible increase appeared.
Some countries would feel the squeeze more
The spare cash is not spread evenly across the currency bloc, and that is where the policy starts to bite unequally. In Italy, Spain and Portugal, banks hold excess liquidity worth only about three to six times their respective reserve requirement. In France and Germany, by contrast, the multiple sits closer to 15.
For now, cash still moves around the Eurosystem relatively smoothly, so a redistribution of liquidity is broadly keeping the machine running. Even so, the gap in those multiples makes clear that certain jurisdictions would feel a tighter squeeze than others if the requirement were raised, since the lower multiple countries have far less room to spare.
The uneven burden on smaller banks
Distribution is uneven not only between countries but between individual banks, a concern flagged the first time the ECB floated the idea of lifting the requirement. On that earlier occasion the proposal was for an increase of even more than a simple doubling. The crucial mismatch is this: the banks that actually sit on the excess liquidity are not necessarily the same banks that hold the deposits. That matters because deposits are the base on which a bank's reserve requirement is calculated. The lenders carrying disproportionately large deposit bases tend to be smaller institutions, and they are the ones that would end up penalised by a higher requirement, even though they may not be the banks flush with spare cash.
What it means for money markets
Taken together, the message is nuanced. Doubling the reserve requirement would not, on its own, upend a system awash with €2.2tr of spare cash. But it would move the euro area closer to the point where funding rates react more keenly, it would press harder on Italy, Spain and Portugal than on France and Germany, and it would fall most heavily on smaller, deposit heavy banks. That combination is why a seemingly dry adjustment to reserve rules is being watched so closely by anyone trading euro funding markets.
