A forex fix is a benchmark exchange rate set from market prices collected during a short window at a fixed time each day. It is used to value portfolios, settle transactions, and execute currency orders at one agreed rate.
The fixing rate is calculated from trades and quotes in the observation window, using a median, an average, or a benchmark provider's method. Because order flow concentrates around the fixing time, the affected pairs can see a short burst of volatility.
Banks, asset managers, corporations, and index providers use the fix to standardise currency conversion and cut pricing disputes. Traders watch the fixing windows, such as the London 4pm fix, because the concentrated flow can move prices briefly.
A global fund needs to convert euro exposure into US dollars for its end-of-day valuation. It uses the official EUR/USD fix as the benchmark rate.
With the fix set at 1.0850, the fund values its euro exposure at one euro = 1.0850 US dollars for that valuation.