"In the end, fiscal-cliff concerns dominated. No deal meant more worry, and we sold off," sighed Schaeffer's Senior Technical Strategist Ryan Detrick. The Dow Jones Industrial Average (DJI) languished below breakeven throughout the day as everyone began ticking down the hours remaining until the calendar turns, bringing with it potential tax hikes and spending cuts. Anxiety accelerated as the closing bell approached, and the Dow finished on the downside of 13,000 for the first time since Dec. 4.

Continue reading for more on today's market, including:

• Why a break of this level on the S&P 500 Index (SPX) would lead Senior Trading Analyst Bryan Sapp to reconsider his bullish bias.
• Option Idea of the Week: One potential trading approach for Microsoft (NASDAQ:MSFT) bears.
• Who gets hurt through high-frequency trading? Schaeffer's contributor Adam Warner shares his thoughts.

• Reassuring words from the Oracle of Omaha, legal woes for Apple Inc. (NASDAQ:AAPL) in China, and a dressing down for the U.S. government via our Tweet of the day.

It was a mirror image of Thursday's session, with selling pressure on the Dow Jones Industrial Average (DJIA) intensifying into the closing bell. The blue-chip average visited its intraday low of 12,926.86 around 3:50 p.m., and closed off 158 points, down 1.2%, below the round-number 13,000 mark. All 30 Dow components suffered losses, with Hewlett-Packard (NYSE:HPQ) shedding the most, down 2.6%. At the top of the heap was American Express (NYSE:AXP), backsliding just 0.04%. On the week, the Dow surrendered 1.9%.

Elsewhere, the S&P 500 Index (SPX) suffered a 15.7-point, or 1.1% drop, but managed to hold narrowly above the 1,400 level. The Nasdaq Composite (COMP) gave back 25.6 points, or 0.9%. The SPX was off 1.9% for the holiday-shortened week while the COMP dropped 2%.

The CBOE Market Volatility Index (VIX) benefited from today's increased volatility, of course, leaping up 16.7% or 3.3 points to close at its highest point since mid-June. On a weekly basis, the index surged 27.4%.

A Trader's Take:

"In the end, fiscal-cliff worries dominated. No deal meant more worry, and we sold off," said Detrick. "The economic data, however, wasn't too bad. The Chicago purchasing managers index [PMI] and home sales were both better than expected," he noted. "Of course, it didn't matter because we had no fiscal-cliff deal in place, but under the surface, the economic data across the board has been pretty good. I wish I had more to say," Detrick continued, "but I'm just tired of the fiscal-cliff drama and can't wait for it to be over with so we can all move on with our lives."

3 Things to Know About Today's Market:

• The daily fiscal-cliff update offered more of the same inertia. President Barack Obama was scheduled to convene with congressional leaders for the first time since Nov. 16 at 3:00 p.m., but a quick resolution was not expected. In fact, reports shortly before the close indicated the commander in chief was unwilling to submit a new offer from his side of the fence. A House vote is rumored for Sunday night, however, and eternal optimist Warren Buffett believes a resolution is (eventually) likely, as he told BBC Radio, "In the end, 535 people in Washington will not thwart the wishes of 312 million Americans."
• The National Association of Realtors' pending home sales index increased by 1.7% in November to a reading of 106.4. This edged out the 1.2% rise expected by economists. On a year-over-year basis, the index climbed 9.8%, and is at its highest point since April 2010. Also, the Department of Commerce revised building permits marginally higher to show a 3.7% increase in October, to a seasonally adjusted rate of 900,000.
• Mediators have bought some time for importers on the East and Gulf Coasts, as an impending strike of International Longshoremen's Association members was delayed by 30 days. A work stoppage -- the first of its kind since 1977 -- would be unwelcome news for retailers, especially those who rely on shipments coming into the ports ahead of the busy gardening season.

Plus ... SeaWorld Entertainment will be going public via private equity firm Blackstone Group. Blackstone bought the theme park chain in late 2009, and has turned it around significantly during the past three years. In 2009, SeaWorld booked a loss of $58 million, and through the first three quarters of 2012, the chain had collected $86 million in profits. This reversal has come at a profound cost, however, as Blackstone has invested heavily into sprucing up the chain's 11 parks, and has assumed SeaWorld's sizable debt. A date for the proposed IPO has not yet been announced.

Today's Top Tweet:

" The courage the Greeks displayed in voting for their own austerity is in stark contrast to what is happening in the US now"
@VIXandMore, (Bill Luby), 12:29 p.m.

5 Stocks We Were Watching Today:

1. Apple Inc. (NASDAQ:AAPL) will pay a $160,000 fine to resolve copyright-infringement allegations in China.
2. Netflix (NASDAQ:NFLX) bears employed a short-term bear put spread in anticipation of a plunge in the shares.
3. Optimistic option players are looking for a rebound in Green Mountain Coffee Roasters (NASDAQ:GMCR) shares.
4. Call buyers targeted a new annual high in Citigroup (NYSE:C).
5. Research in Motion (NASDAQ:RIMM) options bears keep trying to call a top.

Question of the Day:

Q: Why are short interest numbers important?
A: Short interest is a measure of shorting activity by equity traders, and is often a good gauge of overall investor pessimism. As contrarians, we see rising short interest on a technically strong security as a potentially bullish sign. If the stock continues higher, traders who shorted the stock may wish to exit their position by buying the shares, perpetuating a short-covering rally, also known as a "short squeeze." For downtrending stocks, however, increasing short interest can be a warning sign, as a stock may suffer additional losses as bearish investors increase their shorted positions.

For a look at today's options movers and commodities activity, head to page 2.