There are some indexes and market indicators that just make more sense when charted in the inverse. For example, when charting the Volatility Index ($VIX), high values indicate bearishness while low values indicate bullishness. In this case, it feels more intuitive to invert this chart so that bullish values are at the top and bearish values are at the bottom.
You can add a minus sign to the front of any ticker symbol to chart the true inverse of that dataset. For instance, “-$VIX” will create such a chart. Click here to see the chart for "-$VIX", the inverse of $VIX.
Alternatively, you can choose to create a reciprocal chart, which does not match the y-axis values of a true inverse but still approximates the line of the original chart. For instance, charting "$ONE:$VIX" will create the reciprocal of the $VIX chart.