The Dow Industrial Average, down 369 points at the lows of Wednesday's session, posted its worst decline since November 2011.
It's a broad decline for the markets. All 10 S&P sectors are down more than 1 percent. If losses hold, it will be the first time since Dec. 8, 2011, that all 10 sectors end with declines of more than 1 percent.
And if the Dow closes below 13,000, it will be the first time since Aug. 2, 2012.
Downbeat comments from ECB President Mario Draghi regarding Germany's outlook, the U.S. presidential election, and Apple's slide are all partly responsible for the sell-off.
In fact, selling accelerated shortly before 11 a.m., when Apple fell into bear market territory — dropping more than 20 percent from its recent all-time high of 705.07 on Sept. 21, 2012.
Certain "Obama" sectors are among the worst performers, with heavy volume backing their declines. The Financial Sector SPDR ETF, for example, is having its worst day since May's lackluster jobs report was released on June 1. The exchange traded fund is booking heavier-than-normal volume, with more than 70 million shares changing hands as of early afternoon.
Other weak sectors include coal stocks and defense names. Both sectors are sliding on heavy volume as they are perceived to be more favorable under what could have been a Romney administration.
Markets have performed unfavorably both days following Obama's presidential victories. In fact, back on Nov. 5, 2008 — the day after Obama was first elected — the Dow closed down almost 500 points.
Excluding 2008, the only other time stocks have performed as poorly the day after a presidential election in the last 60 years was on Nov. 3, 1948, when the Dow dropped 3.85 percent as Harry Truman claimed victory over Thomas Dewey.
The values for Nov. 7, 2012, are based on the numbers at the lows of the session.
CNBC's Market Data Analyst contributed to this story.