The S&P finished a 23.3% year with its worst last week (-2.62%) since 1937, when it dropped -4.61%. The last week is defined as the period from Christmas to the end of the year (Dec 24-31). There aren't many
strong analogs to draw insights from, but below are the four instances,
post-1930, of a double-digit year ending with a 1% loss in the final
week.
» Five trading days later, each of those periods saw an average gain of 2.53%. «
It is worth noting that five trading days later, each of those four five-day periods saw positive returns, with an average gain of 2.53%. Additionally, the 1% daily moves in those subsequent five days were 7-1 in favor of the positive side. This provides some modest support for a potential reversal bounce next week, following this week's end-of-year portfolio rebalancing and tax-selling selloff.