Conceptually, Wall Street is Irrational and Stocks Are Poor (at best) Long-Term Investments

Follow the logic:

US federal government shuts down, stocks go up.

US Dollar collapse: stocks go higher (but inflation kills your purchasing power).

Nuclear war: stocks go ballistic (parabolic path, but the world is mostly ash).

TEOTWAWKI: Stocks take off towards infinity (no way to cash out, i.e, can't take it with you, though).

Ergo, bad news is good news, again.

And you thought investing was easy...

At the Close, Friday, January 19, 2018:
Dow: 26,071.72, +53.91 (+0.21%)
NASDAQ: 7,336.38, +40.33 (+0.55%)
S&P 500: 2,810.30, +12.27 (+0.44%)
NYSE Composite: 13,384.13, +68.55 (+0.51%)

For the Week:
Dow: +268.53 (+1.04%)
NASDAQ: +40.33 (+0.55%)
S&P 500: +24.06 (+0.86%)
NYSE Composite: +90.12 (+0.68%)