Close this search box.

Table of Contents

Euro Overnight Index Average (Eonia)


The Euro Overnight Index Average (EONIA) was a financial benchmark that represented the weighted average of unsecured overnight lending transactions in the Eurozone. Established by the European Central Bank, its purpose was to serve as a reference rate for overnight loans in the European Union. However, since 2020, EONIA has been replaced by the Euro Short-Term Rate (€STR).


The phonetic pronunciation for “Euro Overnight Index Average (Eonia)” is:- Euro: Yoor-o – Overnight: Oh-ver-nite- Index: In-deks- Average: Av-er-ij- Eonia: Ee-oh-nee-ah

Key Takeaways

Here are three main takeaways about Euro Overnight Index Average (Eonia):

  1. Definition: Eonia refers to an effective overnight interest rate computed as a weighted average of all overnight unsecured lending transactions in the interbank market. It is an essential benchmark for financial instruments.
  2. Function: Eonia is used to measure the cost of borrowing in Euros overnight and is also instrumental in setting the interest rates for financial instruments, including the pricing and the valuation of Euro-denominated derivatives.
  3. Revision: To reflect the evolving structure of European money markets and overcome the limitations of Eonia, the European Central Bank (ECB) introduced a new reference rate, the Euro Short-Term Rate (ESTR), which has replaced the Eonia from January 2, 2022.


The Euro Overnight Index Average (Eonia) is a critical aspect in the financial market as it serves as the primary benchmark for unsecured short-term euro lending. Financial institutions use it as a reference rate for an extensive array of transaction types, including derivatives contracts, adjustable-rate mortgages, and other short-term interest rate products. Accurate, transparent, and reliable, Eonia reduces the investment risk by providing a standardised, reality-based overnight rate, facilitating liquidity management and hedging against interest rate fluctuation. Hence, its importance lies in enabling a smoother functioning of the European financial market and indirectly influencing the broader European economy.


The Euro Overnight Index Average (Eonia) is a critical monetary policy tool used by the European Central Bank (ECB) to influence banking operations. As an interest rate benchmark, Eonia functions as a barometer of the liquidity condition and transmission of monetary policy in the Eurozone. Specifically, its purpose is to reflect the overnight borrowing costs for banks within the Eurozone. Since Eonia is calculated as a weighted average of all overnight unsecured lending transactions in the interbank market, it provides a reliable measure of the effective cost of overnight lending in the Eurozone, helping the ECB to manage inflation.Eonia also serves as a reference rate for a range of financial products, including adjustable-rate mortgages, commercial loans, and interest rate swap contracts. In essence, it forms the basis for calculating interest on these products. For businesses and investors, having an accurate and reliable benchmark interest rate like Eonia is critical for managing interest rate risk and forming expectations about future interest rate movements. Eonia, therefore, plays an integral role in the development of effective financial and investment strategies in the Eurozone.


1. European Central Bank: The European Central Bank (ECB) uses Eonia as one of the key references for setting monetary policy in the Eurozone. Eonia helps the ECB to understand the prevailing short-term lending rates between banks, which further assists them in determining the interest rate level for the entire market. By analyzing Eonia, ECB continues to provide a low-interest rate environment to prevent any financial stability risk in the Euro area.2. Asset Management Firms: Asset management firms such as BlackRock or Vanguard often use Eonia to hedge against interest rate risks. If these companies anticipate a change in short-term interest rate dictated by Eonia, they invest in certain financial products that inversely correlate with Eonia to mitigate their risks. 3. European Commercial Banks: Banks in the Eurozone, such as Deutsche Bank or BNP Paribas, make overnight loans to each other. The interest rate charged on these loans is often referenced to Eonia. For instance, if bank AAA lends to bank BBB overnight, they may agree upon an interest rate that is Eonia + 0.05%, meaning the rate derives from that day’s Eonia rate plus an additional 0.05%. These interbank loans are critical for liquidity management and are a key component of the banking sector.

Frequently Asked Questions(FAQ)

What is the Euro Overnight Index Average (Eonia)?

The Euro Overnight Index Average (Eonia) is a measure of the effective interest rate prevailing in the Euro interbank overnight market.

How is Eonia calculated?

Eonia is calculated as a weighted average of all overnight unsecured lending transactions conducted in the interbank market, initiated in Euros by the panel banks.

What is the main use of Eonia?

Eonia primarily serves as a benchmark rate for financial instruments, such as short-term interest rate futures contracts, and for the Euro area money market.

Is Eonia subject to change?

Eonia changes on a daily basis, reflecting the constant fluctuations in the overnight lending rates offered by European banks.

Who manages and measures Eonia?

Eonia is published by the European Money Markets Institute (EMMI). The Eonia rate is generally published by the EMMI at about 7 p.m. (CET) on each TARGET trading day.

What does Eonia indicate about the economy?

Eonia provides a representation of the state of liquidity in the market and prevailing financial market conditions. It is also indicative of the interbank credit levels in the Euro zone.

How does Eonia affect financial institutions and businesses?

Changes to the Eonia rate can directly impact the costs that financial institutions and businesses face when borrowing from other banks or financial entities. It can affect the interest rates on products such as loans, mortgages, and savings.

Has Eonia been replaced?

From 2 October 2019, Eonia has been replaced by the Euro Short-Term Rate (€STR), although Eonia will continue to be published until 3 January 2022, under a methodology that makes it track the €STR.

Related Finance Terms

Sources for More Information

About Our Editorial Process

At Due, we are dedicated to providing simple money and retirement advice that can make a big impact in your life. Our team closely follows market shifts and deeply understands how to build REAL wealth. All of our articles undergo thorough editing and review by financial experts, ensuring you get reliable and credible money advice.

We partner with leading publications, such as Nasdaq, The Globe and Mail, Entrepreneur, and more, to provide insights on retirement, current markets, and more.

We also host a financial glossary of over 7000 money/investing terms to help you learn more about how to take control of your finances.

View our editorial process

About Our Journalists

Our journalists are not just trusted, certified financial advisers. They are experienced and leading influencers in the financial realm, trusted by millions to provide advice about money. We handpick the best of the best, so you get advice from real experts. Our goal is to educate and inform, NOT to be a ‘stock-picker’ or ‘market-caller.’ 

Why listen to what we have to say?

While Due does not know how to predict the market in the short-term, our team of experts DOES know how you can make smart financial decisions to plan for retirement in the long-term.

View our expert review board

About Due

Due makes it easier to retire on your terms. We give you a realistic view on exactly where you’re at financially so when you retire you know how much money you’ll get each month. Get started today.

Due Fact-Checking Standards and Processes

To ensure we’re putting out the highest content standards, we sought out the help of certified financial experts and accredited individuals to verify our advice. We also rely on them for the most up to date information and data to make sure our in-depth research has the facts right, for today… Not yesterday. Our financial expert review board allows our readers to not only trust the information they are reading but to act on it as well. Most of our authors are CFP (Certified Financial Planners) or CRPC (Chartered Retirement Planning Counselor) certified and all have college degrees. Learn more about annuities, retirement advice and take the correct steps towards financial freedom and knowing exactly where you stand today. Learn everything about our top-notch financial expert reviews below… Learn More