Session crossovers occur each day at precisely the same time in the forex market and provide another perfect opportunity for the market makers to play their tricks on unsuspecting traders. These are the points at which one major trading centre opens taking over from another or joining it, and in either case these are times when you may see changes or pauses in trend, and whilst the forex market is one which trades on a twenty four hour basis, the sessions then break down into four hour cycles. So when a strong trend develops during London for example, this may often weaken or reverse as the US session begins as was the case here and of course confirmed by volume price analysis.