$USD

Considering the legacy arbitrage between the $USD and commodities, gold, oil, silver and yes, stocks (in modern vernacular a cheap dollar means inexpensive stocks to computers - there are exceptions, especially when $USD based carry trades like $USD/JPY are pushing market risk, but on a long term legacy basis...), beyond whatever else we have collected today (as I'm going through leading Indicators), this $USD vs SPX chart looks very interesting, lets see how it plays out.

$USD in orange vs the SPX in green intraday. The $USD is rather flat as the SPX and other averages make various short term bottoms (like "W" in the Q's), then suddenly the $USD falls and the SPX goes to make a new afternoon high.