When markets get statistically too far out of whack, they must return to long-term equilibrium.

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The spurt in productivity growth in America has pushed up share prices in anticipation of future productivity gains, and also improved the competitiveness of American goods, thus increasing the dollar's long-term equilibrium level.

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As lower costs encourage firms to produce more at any given price (ie, the supply curve shifts from S1 to S2 in the chart), the long-term equilibrium level of output will rise and the price level will fall.

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In the long term, when equilibrium is reached (which of course it never is but the trend is generally towards it) the profit made by each competitor will be, on average, just enough to keep the capital employed which each competitor is using.

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