Everyone talks about the 4 PM London fix for good reason. This is the time of day where large flows collide in the FX market. I have seen close to one billion EUR transacted in a three pip range at this time of day. The liquidity available can be endless, until it is you with the fix order :).

In the NY afternoon fixes are done on every hour. The 4 PM NY fix, when liquidity can really be an issue, is ripe for some good moves should the fix order be of any size. A 200 million GBP fix at 4 PM NY time can move the pair 30 or 40 points. It pays the executing bank to move the market to fix the rate at an extreme on the hour. So when you see these moves in the afternoon and wonder why this is happening, now you know.