Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

It's official – the post FOMC decision euphoria is over! Yesterday's decision to begin the tapering of the Federal Reserve's monthly economic stimulus known as QE3 sent the broad-based S&P 500 (SNPINDEX:^GSPC) to fresh all-time closing highs, but stocks struggled to maintain those gains all day today.

Surprisingly weak economic data helped lead stocks to very modest downside today, with initial weekly jobless claims rising 10,000 to a seasonally adjusted 379,000, which was much higher than economists had forecast. Wild fluctuations in weekly jobless claims aren't an uncommon occurrence around the holiday season due to sporadic hiring, but with this figure approaching 400,000 once again, the chances of the unemployment rate falling below 7% anytime soon may be thrown out the window.

Also, U.S. existing home sales fell to a seasonally adjusted rate of 4.9 million from the 5.12 million reported in the prior month. This marks the third consecutive month of declines, and one of the lowest readings we've witnessed in nearly a year. I believe this drop only reinforces my unpopular opinion that the U.S. consumer has been spoiled with historically low lending rates for far too long, and now they're sitting on their hands as rates have bounced only modestly off their lows, hurting the housing market.

For the day, the S&P 500 dipped by just 1.05 points (-0.06%) to close at 1,809.60.

In a real surprise, struggling overseas wireless telecom service provider NII Holdings (NASDAQ:NIHD) led all stocks to the upside today with a gain of 22.7% despite no company-specific news... today, at least. On Monday, though, NII reported changes in its executive management team including the move of Peter Foyo, formerly the President of Nextel Mexico, to Executive VP of business development for NII. NII also named John McMahon the Interim President of Nextel Mexico, in addition to a few other notable changes. With NII burning through its cash, piling up debt, and reporting significantly wider-than-expected losses, investors are simply cheering any fresh ideas that may emerge from this management shakeup. As for me, I'd still suggest keeping as far away as possible from NII until it drastically reduces its losses and cash burn.

Flat-rolled steel products producer AK Steel (NYSE:AKS) vaulted higher by 15.4% after updating its fourth-quarter guidance. For the upcoming quarter, AK Steel forecast total shipments of approximately 1.4 million tons, which is up from 1.24 million tons in the prior year, and expects to report a surprise profit of $0.02-$0.06 per share compared to last year's $0.12 loss per share. The big driver appears to be significantly lower production costs; but before you get too excited, keep in mind that the average price per ton of steel is expected to fall by roughly 4% year over year.

Finally, global media and Internet company IAC InterActiveCorp (NASDAQ:IAC), best known as IAC, jumped 14% after divulging plans to spin off its group of dating websites into a separate company to be known as Match Group. This new company will consist of Match.com, OKCupid, Tutor.com, DailyBurn, and IAC's investment in SkyIIzone, and will be led by Greg Blatt. Today's reaction higher feeds off of a recent trend by businesses of splitting into separate components in order to make revenue and earnings comparisons easier for investors to understand. I'm a bit unsure where I stand on the company following today's pop, but Wall Street certainly appears impressed.

Fool contributor Sean Williams has no material interest in any companies mentioned in this article. You can follow him on CAPS under the screen name TMFUltraLong, track every pick he makes under the screen name TrackUltraLong, and check him out on Twitter, where he goes by the handle @TMFUltraLong.

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