The coming days are shaping up as being technically significant for the US market outlook, given the potential for a key US index trend change has emerged. The S&P500 index has the potential to generate a technical top formation which is the requirement to generate a technical sell signal. A close below 2039 is required to generate a technical sell signal. The minimum downside technical target in that scenario would be located at 1950. At this stage the index is holding above the 2039 support level - which is the key technical level to watch.