Almost an hour into the US trading day and the Nasdaq 100 index is once gain struggling to post and retain gains on the day.

Markets are effectively a continuous auction between buyers and sellers, who are trying to establish an equilibrium price, at which business can be transacted .

An imbalance in the supply or demand, of either buyers or sellers , tilts the price in the opposite direction to that imbalance.

Price moves until it finds a new equilibrium level, and it usually travels along the path of least resistance as it does so, which for the last few sessions, in the Nasdaq 100 has been lower.