A new upstart has joined the composition of foreign exchange benchmarks. Siren, which began trading in January, hopes to challenge the iron grip that the WM/Refinitiv 16:00 fix has on the spot market.

The siren differs from the 16:00 fix by using a longer viewing window for stores. This has a dual effect, its supporters argue. First, the benchmark will be harder to manipulate. Second, it will be less susceptible to market impacts, meaning tighter prices for users such as pension funds.

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