I’ve seen it two ways. Is it A - spread over average bid/ask or B - spread over dealer ask. USD:GBP - 0.8955 - 0.8993 is it A) 0.0038 / Avg (0.8955+0.8993) = 0.4234% or is it B) 0.0038 / 0.8993 = 0.4226% thx in advance
It can be expressed as a % of the bid, midpoint, or the ask. When in doubt, I would go with the spread over the midpoint.
thx bud