SARON, short for Swiss Average Rate Overnight, is the Swiss franc reference rate for overnight loans. SIX Group calculates and publishes it based on the secured loans that banks grant one another. It tracks the policy rate of the Swiss National Bank (SNB), because the SNB steers precisely this market. On 20 October 2026, SARON stood at -0.05%, against a policy rate of 0% as at 21 October 2026.
This page of our SNB and interest rates guide answers a single question: where does this figure come from, and why does it stick so closely to monetary policy? It draws on the SIX and SNB web pages consulted on 21 and 22 October 2026.
What exactly does SARON measure?
SARON measures the cost of an overnight loan in francs, secured by securities. SIX describes it as the main overnight reference rate for the Swiss franc.
The rate stems from the Swiss repurchase agreement market, also known as the repo market. Banks lend each other francs there against guarantees, known as collateral. Because the loan is covered, SIX describes the counterparty and liquidity risks as negligible.
According to SIX, the rate influences the yield curve of the entire economy. Banks also use it to manage their liquidity on a day-to-day basis. Finally, SIX highlights its role in the SNB's monetary policy and in the stability of the financial system.
How is SARON calculated?
SARON is a volume-weighted average of interest rates. The largest transactions therefore carry more weight in the result than the small ones.
The calculation is based on two types of data, taken from a regulated trading platform:
- transactions actually concluded between institutions;
- binding quotes, that is, offers that commit those who post them.
SIX applies a filter to transactions and quotes to limit the risk of manipulation. The calculation rules are set out in index rules available to the public. According to SIX, the methodology complies with the international standards applicable to benchmarks.
The rate follows the ACT/360 convention: interest accrues on the actual number of days, relative to a year of 360 days. The calendar is that of the public holidays specific to the franc. An index commission, the Swiss Reference Rates Index Commission, plays an advisory role and brings together a range of viewpoints.
Who publishes SARON, and at what time?
SIX is the official administrator of SARON. It guarantees its calculation and publication. The rate was introduced on 25 August 2009, but its historical data go back to 30 June 1999.
Publication begins every day at 8:30, after which the rate is updated every 10 minutes. Three fixings take place each day, at 12h, 16h and 18h Central European Time.
Real-time access remains subject to a fee. Values from the first 24 hours are reserved for licence holders. A public website may only display SARON with a delay of at least 24 hours after the 18h fixing. The historical data, on the other hand, can be downloaded free of charge from the SIX website.
SARON belongs to a broader family, the Swiss Reference Rates. It comprises 32 reference rates, from overnight up to 12 months, plus two indices for overnight. The SNB also lists SARON among the key rates displayed on the home page of its website.
Why does SARON track the SNB policy rate?
SARON tracks the policy rate because the SNB targets exactly the market it measures. Its instruments aim to keep short-term rates in the secured Swiss franc money market close to its policy rate.
The policy rate is the third pillar of the SNB's strategy. The first two are the definition of price stability and the conditional inflation forecast. To reach its target, the central bank has several levers:
- The rate on sight deposits. Banks hold francs in their account at the SNB. Up to a defined threshold, these deposits are remunerated at the policy rate. Above it, the SNB applies the policy rate minus a certain number of basis points.
- Repo transactions. The SNB provides or absorbs liquidity against securities. In doing so, it acts on the quantity of francs available in the financial system.
- SNB Bills. The SNB issues its own short-term securities in two auctions every Thursday, with maturities of 28 to 336 days.
This two-tier system encourages banks to trade liquidity among themselves. It therefore keeps the repo market active, the very market that feeds into the SARON calculation.
Why can SARON fall below 0%?
SARON can be slightly negative even with a policy rate of 0%. On 20 October 2026, it stood at -0.05%, according to figures published by the SNB.
The SNB describes the framework within which this gap arises. When its policy rate is at 0%, a negative rate applies to sight deposits above the threshold. However, the pages consulted quantify neither this threshold nor the reduction applied. Nor do they directly link the gap of 0.05 percentage points to this mechanism: it is a framework for interpretation, not a measurement.
The context of autumn 2026 serves as a dated example. The SNB conducted its assessment of 24 September 2026, and its policy rate stood at 0% as at 21 October 2026. On the sidelines of the IMF and World Bank meetings, its Chairman Martin Schlegel explained that contained inflation in Switzerland had made it possible to leave the policy rate unchanged.
Overnight rate or compound rate: what is the difference?
The overnight SARON covers only one night, whereas contracts run for months. SIX therefore calculates compound rates, which accumulate the daily SARON values over a given period.
| Rate | What it measures | When it is known |
|---|---|---|
| Overnight SARON | The cost of a secured overnight loan in francs | From 8:30, updated every 10 minutes; fixings at 12h, 16h and 18h |
| SARON Compound Rates | SARON compounded over 1 week or over 1, 2, 3, 6, 9 and 12 months | Calculated in arrears, hence at the end of the period; public with a delay of one business day |
| SARON Compound Indices | An index that tracks each of the compound rates | Public with a delay of one business day |
Calculation in arrears has a practical consequence: the rate for a period is only known once that period has ended. It is not set in advance, unlike a rate agreed at the outset.
What does SARON change for a borrower in Switzerland?
SARON serves as the basis for everyday loans. SIX describes it as the benchmark for Swiss mortgages. Its data licence covers the use of SARON for private mortgages, corporate loans and interest rate swaps.
For a household or an SME, SARON is only one component of the rate paid. The contract terms, including the bank's margin, depend on each institution. The sources consulted do not state its level.
An individual can nonetheless check the compound SARON over a period for themselves. Since 15 September 2020, SIX has offered an online calculator intended for non-professionals. It covers any period within the last 12 months, including non-business days, with a delay of one business day. This tool provides a reference figure, not advice on choosing a form of financing.
Key figures
- 0%: SNB policy rate as at 21 October 2026.
- -0.05%: SARON on 20 October 2026, according to the SNB.
- 25 August 2009: introduction of SARON; historical data since 30 June 1999.
- 8:30: start of daily publication, followed by updates every 10 minutes.
- 3 fixings per day: 12h, 16h and 18h.
- 32 rates: reference rates in the Swiss Reference Rates family, from overnight to 12 months.
- 24 hours: minimum delay before any public display of SARON.
What we do not yet know
The sources consulted give no forecast of how SARON will develop. Its future level will depend on the SNB's upcoming decisions, whose direction they do not indicate. Nor do they specify the sight deposit threshold or the reduction applied above it. Finally, banks' margins on SARON mortgages do not appear in any of them.
In this series
Sources
- SIX, SARON (Swiss Reference Rates), page consulted on 22 October 2026.
- Swiss National Bank, home page and key rates, values for 20 and 21 October 2026.
- Swiss National Bank, implementation of monetary policy, page consulted on 22 October 2026.
