Overnight Rate

The overnight rate is the interest rate at which banks borrow from each other for a single day. It is the rate central banks steer with their policy rate, and the benchmark that replaced LIBOR for loans, derivatives and floating rate notes in each of these currencies, which makes it the most direct daily read of monetary conditions.

Each currency has its own benchmark, published by its central bank:

• Euro Area: the euro short-term rate (€STR) from the European Central Bank, since October 2019.
• United Kingdom: the Sterling Overnight Index Average (SONIA) from the Bank of England, since 1997.
• Japan: the uncollateralized overnight call rate, the Tokyo Overnight Average Rate (TONA), from the Bank of Japan, since 1985.
• United States: the Secured Overnight Financing Rate (SOFR) from the Federal Reserve Bank of New York, since April 2018.

None of these sources require an API key. The rates are returned as decimal fractions per annum (0.0244 for 2.44%). Weekly and monthly periods take the rate on the last day of each period (weeks end on Friday).

Also known as: €STR, ESTR, SONIA, TONA, SOFR, overnight interbank rate, risk-free rate.

Overnight Rate in Python

Install the Finance Toolkit with:

pip install financetoolkit -U

Then call get_overnight_rate as shown below.

from financetoolkit import Economics

economics = Economics(start_date='2026-04-01', end_date='2026-09-30')

economics.get_overnight_rate(period='monthly')

Which returns:

Parameters

The function accepts the following parameters:

• countries (list[str] | str | None, optional): The countries to include in the data. Defaults to None.
• period (str, optional): Whether to return the daily, weekly or monthly data. Defaults to “daily”.
• rolling (int, optional): The rolling window size to use for smoothing the data (simple moving average). Defaults to None.
• trailing (int, optional): The trailing window size to use for summing the data over trailing periods (e.g. a trailing-4-quarter sum). Defaults to None.
• growth (bool, optional): Whether to return the growth data or the actual data.
• lag (int, optional): The number of periods to lag the data by.
• standardize (bool, optional): Whether to standardize (Z-Score) the result. When combined with growth=True, standardizes the growth values instead of the raw values. Defaults to False.
• rounding (int | None, optional): The number of decimals to round the results to. Defaults to None.

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