Midday Sunday reports out of Washington DC indicate that "negotiations" on resolving the fiscal cliff have broken down. This presages a major stock market drop in all worldwide markets starting in about five hours when Far East markets open around 7pm Eastern time.
Stock market futures were already down significantly after the market close Friday, following a sharp Friday afternoon selloff.
Monday is not a stock market holiday. American stock markets are open between 9:30 am and 1:00 pm tomorrow. This may be a fun day to sit at home and watch the action. Expect lots of loss-taking because institutional investors like hedge funds and mutual funds will want to protect their gains (or cut their losses) as much as possible. This is a form of "window dressing" as fund managers try to protect their annual and quarterly results. To a lesser extent, there may be tax-driven selling as tomorrow is the last day in 2012 in which one can sell and realize taxable events (gains in 2012, to capture a presumably lower rate since rates are expected to rise sharply starting January 1st; taking losses is also advantageous as a writeoff against any realized gains).
We may see a manic panic rush to the exits as people covering the trading desks for others still on vacation get panicked calls from higher-ups to dump stocks, bonds, possibly any asset class. One notable asset class exception may be derivatives and exchange-traded funds which attempt to move inversely to the market. Holders in those funds -- or others which fled stocks in anticipation of a fiscal cliff crisis actually occurring -- may be partying well in advance of the ball being dropped tomorrow.