
Click for a larger image
There are two points with the chart above.
First, notice that volume has been decreasing since the beginning of the rally. That tells us that fewer and fewer people are trading in the market. Part of the reason for this might be that a lot of people allocated capital at the low points in March and are simply holding onto gains. But some of it is also that we're not seeing a huge influx of new capital.
Secondly, notice the curve of the chart. The initial move from the March lows was strong. But notice the angle of the rally has slowly become more and more horizontal. Finally, notice that for the last month and a half prices have been stagnant at the top of the range, unable to move above ~111.
It is possible that some of this is simply the end of the year. Traders have some big gains, from the year, so they have hair triggers when it comes to selling. But it could also mean the market is stalling for now.