The Weekly chart of the S&P 500 (SPY) is arguably the most important chart out there right now:

Click to enlarge

SPY_Weekly_9.30.2014

The momentum divergences and decreasing volume at each successive high are certainly worth making note of. Notice that the weekly RSI-14 has not fallen below the median line in nearly two years and there is a clearly defined uptrending channel drawn from the November 2012 low. A breach of the channel to the downside and a move below the median line in the RSI would be bearish to say the least.....

It also interesting to note that as of now the S&P 500 quarterly chart is printing a 'doji' candlestick for the quarter ending today - this is especially noteworthy given that this candlestick is forming after an extended uptrend and 8 consecutive up quarters.