How S&P 500 relates to the dollar

An article from a stock forum

I have talked quite a bit of late about the market internals of the S&P 500, and last week I flagged a concern that overall breadth had been deteriorating in the index as its price was rising. This suggested that very few stocks were pulling the index higher, with the majority of them losing ground each day.
That has led us to today, where we are getting a test down to the 50-day moving average. This is an important uptrend support line proxy for the entire move off the March lows and therefore its ability to come through a test on the upside is key for the bullish thesis.
Beyond the S&P 500, the U.S. Dollar Index has also been experiencing a test of its own. This time however, that test is the mirror opposite of the S&P 500, as you can see by the graph.
The 50-day moving average in both cases is important. We can quite easily see the inverse correlation between the way the dollar moves and the S&P 500 moves. The dollar now is coming up to its 50-day moving average, which, in opposition to the S&P 500, is acting as a downtrend resistance line.
So far in both cases, when the moving average is touched and tested, the asset in question reacts away from the line in the opposite direction.
In the case of the S&P 500, price goes up while the dollar goes down. As we can see from the graphs, although the correlation is not perfect, this inverse directional relationship is important nonetheless between the two assets.
A big potential trend change for both indexes would be if the respective 50-day moving averages are broken. If that happens, we could see a reversal for both assets--a lower S&P 500 and a higher dollar.
(Chart data provided by Thomson Reuters)