So there's a few good reasons this is a good short.
1. Using the Rsi you can see it's being pinched against the 70 levels very tightly now. It should break through that trend line holding as support. 2. Price has reached a Resistance level set by the 3 peaks that occurred in October-December 3. Pretty good Inverted Hammer that occured on 2/25/19 4. Spx500 has had a very strong rally since the new year and it's about time it humbles itself.
You can take profits at the daily 200 EMA and take profit 2 would be set at the downward trendline.