In the face of the COVID-19 crisis, massive purchases of 
government bonds by the ECB  through its Pandemic Emergency Purchase 
Programme, or PEPP, were crucial for averting a financial crisis. 
However, as a side effect, the PEPP diminishes even further the supply 
of euro denominated safe assets available to other central banks. 
This creates a conundrum for the ECB. If it continues buying 
government bonds to support the euro area economy, it limits the 
availability of assets for use as foreign exchange reserves by central 
banks still further.  Based on Eichengreen and Gros (2020), we propose a
 way out: the issuance of ECB  Certificates of Deposit (ECBCDs).1
Strengthening the international role of the euro
Strengthening the international role of the euro is official policy 
of EU institutions.  According to its 2020 work programme, the European 
Commission intends to adopt a strategy of “Strengthening Europe’s 
Economic and Financial Sovereignty”.  The ECB  has similarly embraced 
this aim (Panetta 2020).  
One measure often used to gauge the international role of the euro is
 its share in foreign exchange reserves.  This share is in the range of 
20% to 25%, or about one third of that of the US dollar.   It is often 
argued that the euro’s share is so low because there do not exist enough
 euro-denominated safe assets (e.g. Valla 2019, Habib et al. 
2020).  Reserve managers, the argument goes, prefer to invest in 
low-risk, liquid government bonds. In practice, an AAA/AA rating is 
needed to qualify for safe asset status.  Only four euro area countries 
have this rating (FR, DE, NL and AT), and their combined marketable debt
 of €5 trillion is dwarfed by the close to $20 trillion of US Treasury 
bonds outstanding.  
Moreover, until now, there has not existed a significant supply of 
safe common euro area assets. The fiscal measures adopted by the EU and 
its member countries hold out promise that this supply might now 
increase.  However, any such tendency is being offset by the ongoing 
asset purchases of the Eurosystem.
ECB  bond buying and the supply of safe euro assets
Between 2014 and 2018, the ECB  purchased roughly €2.2 trillion of 
government bonds under the PSPP.  Roughly 60% of this was spent on the 
bonds of the four countries supplying safe assets. Since these bonds are
 now held by the Eurosystem and are no longer on the market, this has 
effectively reduced the scope for international investors to hold euro 
assets.
Table 1 shows the impact of the PSPP up to now: a drop in the 
marketable amount of about €1.4 trillion between 2014 and 2019.  (The 
total includes supranational bonds of €200 billion.)
In addition, European banks are required to hold ‘high-quality liquid
 assets’ in proportion to their balance sheets, for which public sector 
bonds are their main source.  Hence another significant fraction of euro
 area public debt securities is absorbed by the banks (about €1.5 
trillion by end 2019).  Together with other euro area sectors 
(insurance, etc.) amounts available for international investors, such as
 reserve managers, were limited to €1.1 trillion at end-2019 (fourth row
 of Table 1). 
The PEPP initiated in March 2020 constitutes an extension of the 
PSPP.  So far this year, the supply of safe government bonds available 
to global reserve managers has actually declined (from €1.1 to €1.0 
trillion) because the Eurosytem and other euro area residents have been 
buying safe assets more quickly than governments have issued them.
Looking forward, the €1.35 trillion of additional purchases planned 
by the ECB  (equivalent to 12% of euro area GDP) over the next 18 months 
are larger than the expected deficits of euro area member states over 
the same period. 
The continuing operation of the PEPP will also reduce the supply of 
common safe assets expected from the Next Generation EU financial 
package of support to member states. The Eurosystem is likely to 
purchase as much as half of the (maximum of) €850 billion of common 
bonds that the EU is planning to issue.2  The additional net 
supply of euro safe assets may thus increase only by about €425 billion 
(equivalent to 4% of global reserve holdings).3 
Table 1 Stock of debt securities outstanding available for the rest of the world (not held by euro area residents)

Note: As supplier of safe euro assets to the market, 
we considered the AAA euro area countries (Germany, France, the 
Netherlands, and Austria) and the supranationals.  To obtain the amounts
 displayed in the table we proceeded on three steps. First, from the 
Government Finance Statistics (GFS) we retrieved the total amount of 
debt securities outstanding for the suppliers of safe assets considered,
 for June 2020, December 2019, and December 2014. Second, from the 
Securities Holding Statistics (SHS) we retrieved data on the total 
amount of debt securities issued by the governments of the safe assets 
suppliers mentioned above and held by euro area residents for 2020Q2, 
2019Q4, and 2014Q4. These data series do not include the debt securities
 held by the Eurosystem, so we considered the PSPP and the PEPP 
breakdown history database, to obtain cumulative data until June 2020 
and December 2019 on the securities issued by the safe assets suppliers 
under analysis and held by Eurosystem under PSPP. Finally, we subtracted
 from the total outstanding amount of debt securities, both the amount 
held by the Eurosystem under PSPP and PEPP (if applicable) and the 
amount held by euro area residents. The numbers on the first four rows 
are expressed in billion EUR, the numbers on the last two rows are in 
billion USD. 
Source: Own calculations based on ECB  
Statistical Data Warehouse (Securities Holding Statistics, PSPP 
breakdown history and Government Finance Statistics) and TreasuryDirect.
How to increase safe assets  
The ECB  (or rather the Eurosystem) finances its bond purchases by 
issuing bank deposits.  These deposits are not tradable outside the 
banking system (central banks can’t hold them as foreign 
reserves).  Thus, the PEPP reduces the supply of euro safe assets to the
 market and enlarges bank balance sheets, on both counts making it more 
difficult for central banks around the world to invest their reserves in
 euros.  
We propose a simple solution to this conundrum: the ECB  should make 
its liabilities tradable.  The easiest way would be for the ECB  to issue
 tradable Certificates of Deposit (ECBCDs).  ECBCDs would constitute a 
euro area safe asset par excellence. They would be an attractive way for
 foreign central banks to hold reserves in euros, provided of course 
that the certificates in question can be traded globally and are issued 
in a sufficiently large amount to create a liquid market.
One would not need to invent a new legal basis for this instrument.4 
 Item 4 of the balance sheet of the Eurosystem is 'debt certificates 
issued'.  The ECB’s own definition for this item is as follows:
“ECB  debt certificates’ means a monetary policy instrument used 
in conducting open market operations, whereby the ECB  issues debt 
certificates which represent a debt obligation of the ECB  in relation to
 the certificate holder”.
ECBCDs would be attractive because they would not be bottled up in 
the euro area banking system. Normally only banks (officially monetary 
financial institutions, or MFIs) are entitled to hold accounts with the 
ECB  or the National Central Banks of the Eurosystem.  The legal 
provision governing the assets in these accounts is clear:
“The ECB  shall not impose any restrictions on the transferability of ECB  debt certificates”. 
This implies that there would be no legal obstacle for a foreign central bank to acquire ECBCDs.5 
Neither would market size be a problem.  At present,6 
liabilities to banks are some €3 trillion euro for the Eurosystem as a 
whole.  This suggests that the ECB  could easily issue €1 trillion in 
ECBCDs without having to worry that this amount would have to be reduced
 in the foreseeable future.  
The present legal basis for ECBCDs limits their maturity to 12 
months, which might limit their attraction. IMF  data show that central 
banks hold about $1.5 trillion of reserves in the form of deposits, with
 about two thirds held at other central banks and one third held at 
commercial banks. ECBCDs should constitute an attractive substitute for 
deposits held at euro area national central banks (or even deposits at 
the Bank for International Settlements). This should ensure a small but 
significant market for short-term ECBCDs. 
However, the market for medium maturities is evidently much larger. 
McCauley (2020) shows that Treasury bills (with a maturity of less than 
one year) account for only about 1/10th of total Treasury holdings (with
 bonds constituting the remainder). The Swiss National Bank reports that
 the average maturity of its fixed-income investments is over 
four years. All this indicates that it would be important to offer 
foreign central banks an instrument with a maturity of several years.
One concern with the ECB  in issuing longer-dated CDs is that such 
issuances would make it difficult to reverse the asset purchases or to 
reduce lending to banks. However, the balance sheet of the Eurosystem is
 unlikely to shrink even if the current crisis is overcome. The ECB  is 
granting loans of three years to banks under the targeted longer-term 
refinancing option (TLTRO). There is thus little danger that the amount 
of ECBCDs outstanding could be larger than lending to banks and the 
amount of assets held, suggesting that it should be possible to issue 
three-year ECBCDs. 
One objection to this proposal is that issuing these certificates 
could be seen as draining liquidity from banks, which could be 
interpreted as a tightening policy. But the counterpart of the issuance 
of tradable ECBCDs would be lower deposits at the ECB  which carry a 
negative rate and thus diminish bank profits.  Although this problem has
 been partially addressed by the tiering of the deposit rate, it could 
be reduced further, thus alleviating the tax on bank profits implicit in
 negative deposit rates and make the monetary stance more effective. One
 could therefore argue that the issuance of ECBCDs is entirely 
compatible with the ECB’s primary mandate of maintaining price stability
 (as well as its subsidiary mandate of supporting the general policy of 
the EU).
Conclusions
Large-scale bond buying under the PEPP reduces the supply of safe 
euro assets to the market.  This effect could be neutralised, at least 
in part, were the ECB  were to issue its own Certificates of Deposit.
The legal framework for issuing Certificates of Deposit already 
exists. The ECB  could immediately issue between €2 trillion and €3 
trillion of ECBCDs, thereby significantly increasing the supply of euro 
safe assets to the market and helping to internationalise the euro. 
Authors’ note: Angela Capolongo is now working at the European 
Stability Mechanism (ESM). This column was completed before she joined 
the ESM. The views expressed here are solely those of the authors and 
are not to be reported as those of the ESM.
References
Eichengreen, B (2011), Exorbitant Privilege: The Rise and Fall of the Dollar and the Future of the International Monetary System, Oxford University Press.
Eichengreen, B and M Flandreau (1996), “Blocs, Zones and Bands: 
International Monetary History in Light of Recent Theoretical 
Developments”, Scottish Journal of Economics 43(4): 398-418.
Eichengreen, B (2016), “The future of the international monetary and financial architecture”, Conference proceedings.
Eichengreen, B, A Mehl and L Chitu (2018), How Global Currencies Work, Princeton University Press.
Eichengreen, B (2020), “Dollar Sensationalism”, Project-syndicate.org, 12 August.   
Eichengreen, B and D Gros (2020), “Post-COVID-19 Global Currency 
Order: Risks and Opportunities for the Euro”, Study for the Committee on
 Economic and Monetary Affairs, Policy Department for Economic, 
Scientific and Quality of Life Policies, European Parliament, September.
Hardy, D C (2020), “ECB  Debt Certificates: the European counterpart 
to US T-bills”, Department of Economics Discussion Paper No. 193, 
University of Oxford.
McCauley, R N (2020), Safe Assets and Reserve Management, Chapter 8 in J Bjorheim (ed.), Asset Management at Central Banks and Monetary Authorities, Springer International Publishing.
Panetta, F (2020), “Unleashing the euro’s untapped potential at global level”,  Member of the Executive Board of the ECB, Meeting with Members of the European Parliament, 7 July.
Habib, M M, L Stracca and F Venditti (2020), “The Fundamentals of Safe Assets”, ECB  Working Paper no.2355, January.
Valla, N (2019), “Safe Assets in a Monetary Union”, Presentation to 
the CEPR  Research and Policy Network  on European Economic Architecture, 
16 April.
Endnotes
1 Previously, Hardy (2020) also proposed the introduction of the ECB  
certificates, that could serve as counterpart to the short-term US 
assets, such as T-bills.
2 The
 (self-imposed) limit of Eurosystem holdings of national government 
bonds is one third.  For so-called ‘supra-national’ debt it is 
half.  Close to one half of ESM  bonds are held by the Eurosystem (though
 not by the ECB  as a legal entity). Supra-national bonds are important 
for national central banks that could not otherwise buy their share of 
national debt because they would exceed the one-third limit.
3 Another unknown is the size of bank balance sheets and their demand
 for sovereign debt.  If households continue to accumulate bank deposits
 but the demand for credit remains weak, banks will have little choice 
but to accumulate even more government securities (which have a zero 
risk weight).  Over
 the first six months of 2020, commercial banks increased their holdings
 of Euro Area government debt securities by more than €300 billion, an 
amount similar to purchases by the Eurosystem (somewhat more than 400 billion). 
4 The legal base for this instrument was created in 2015 and can be found here (2.4.2015 EN Official Journal of the European Union L 91/21 ).
5 Certificates of Deposit are not unusual instruments for a central 
bank to issue.  A case in point is Denmark, where the interest rate on 
certificates of deposit is the central bank’s main policy instrument. In
 the Danish case this instrument is very short term: loans to banks and 
CDs have the same maturity, namely one week (https://www.nationalbanken.dk/en/monetarypolicy/instruments/Pages/Default.aspx). The Swedish national bank also uses certificates of deposit as its main policy instrument.
6 August 2020 (https://www.ecb.europa.eu/press/pr/wfs/2020/html/ecb.fst200804.en.html)