SPX so strong since 2009, probably a number of reason why but the why doesn't really matter. Although the chart looks very extended it's too strong to short imo. This kind of chart tends to trigger a psychological bias in us that it 'must' be about to turn around. In reality it might not. Bad news doesn't seem to dent it so it's not immediately obvious what will turn the tables. Trying to guess at that and time a short is not a smart trade. Better to hold it if you have it, or buy dips along the trend line. If the trend line breaks, maybe time to reassess.