Take a look at the daily charts of the Nasdaq Composite and S&P 500 Index, both of which have rallied aggressively over the past few days. The Nasdaq is testing the 50% retracement level along with the 200-day moving average, while the S&P has gapped above both metrics. Both, however, have an area of potential resistance that highlight the last bull counter-rally rejection and a key Fibonacci retracement (61.8% of the latest range).

For the S&P 500, the key level to watch is 2812, which is awfully close to the 50-day MA at 2833, which served as key support over the past summer. If over the next few days, this region manages to contain the recent rally, it could be setting-up for a key lower top to form.

That said, the rally in stocks has been rather impressive and is still showing significant momentum to the topside. Ideally, a hesitation of some sort (in strength) would be required to even hint of an imminent reversal. Thus, the most likely scenario, in this case, is a bullish exhaustion, which means either a large intra-day candlestick or bar that closes at or near the highs, that is near 2812 or 2833, or simply have a daily close near or just below these two key levels.