Trader Mike answers in this post:
I've still got my eyes on the resistance around the highs of October 17th, 20th and 21st (depending on which index you're looking at). Until the bulls can produce a high above those highs I have to consider this rally nothing but a retracement in a larger downtrend.
I annotated my own chart adding today's continued confirmation of the S&P 500's downward trend:
In addition to the stochastics showing the S&P overbought, the RSI(2) also indicates the S&P is overbought.