SPY Outside Negative Reversal
The horrid events in San Bernardino coincided with a pick-up in selling pressure in stocks. Based on similar nightmares, that is likely nothing more than coincidence.
The excuse was most probably a statement by Fed Chairwoman Yellen, but whatever the reason, the S&P 500 is putting in an outside negative reversal.
Previous reversals have had the most consistent returns two days later, when SPY had trouble rising after the down day, as we can see from Table 1.
Assuming this holds into the close, it argues for a modest negative bias in the short-term.