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.

Following the broad-based S&P 500's (SNPINDEX:^GSPC) worst tumble in weeks is one of the strongest gains the index has delivered in nearly the same amount of time.

Pushing the S&P 500 higher today is significantly stronger-than-expected U.S. retail sales data, especially when auto sales are excluded. According to this morning's reports, retail sales excluding autos increased by 0.7% in December, which was much higher than the broad-ranging estimate calling for a decline of 0.1% to a gain of 0.4% -- and it certainly left November's 0.1% gain in the dust. Although consumers clearly weren't buying as many cars in December, the prospect that other retail sales improved appears to be a distinct possibility.

Between this strong data and a select group of preliminary earnings reports, the S&P 500 managed to trek higher by 19.68 points (1.08%) to close at 1,838.88.

Leading all stocks to the upside today – and certainly putting a grin on my face as my largest portfolio holding -- is Thompson Creek Metals (NYSE:TC) which gained 17.8% after announcing its fourth-quarter and 2013 production and sales results and updating its production outlook. Thompson Creek noted that concentrate production at its recently commission copper and gold mine, Mt. Milligan, produced 10.9 million pounds of copper, 21,100 ounces of gold, and 41,800 ounces of copper through Dec. 31. In addition, molybdenum production from its two active mines jumped 34% from the year-ago period to 30 million pounds. Thompson Creek's management also notes that commercial production of Mt. Milligan – defined as operating at 60% production capacity for 30 days – will occur in the first quarter. An upgrade from Bank of America/Merrill Lynch to "neutral" from "underperform" with a fresh price target of $7 added icing on the cake. In other words, Mt. Milligan, despite its higher-than-expected costs, remains on track and, metal prices willing, could deliver surprisingly strong results this year.

Adding some irony to my cheers is my lone short position, Tesla Motors (NASDAQ:TSLA), which advanced 15.7% after announcing mixed news involving its fourth-quarter deliveries and a Model S recall. On the downside, Tesla released a statement that it plans to recall 29,222 Model S sedans to upgrade the car's charger on overheating fears. However, shares exploded higher after the company also commented that its fourth-quarter deliveries would hit 6,900 vehicles, well ahead of its previous estimates of slightly less than 6,000 vehicles. This figure will put Tesla's revenue estimates well ahead of Wall Street's. On the heels of this news, R.W. Baird upped its price target on Tesla to $187 and raised the stock to outperform. As for me, I will remain short given the ridiculous premium-per-car valuation being divvied out to Tesla in the face of a still small manufacturing effort and a general lack of supportive EV infrastructure.

Finally, biopharmaceutical giant Regeneron Pharmaceuticals (NASDAQ:REGN) galloped higher by 11.8% after its CEO noted at the JPMorgan Healthcare Conference that sales of Eylea will top $400 million in the U.S. in the fourth quarter. That represents less than 10% growth from the sequential quarter, but it's still well ahead of expectations and points to Eylea's dominance in treating wet age-related macular degeneration, as well as for its overseas potential. In addition, Regeneron also announced a joint development with Bayer (NASDAQOTH:BAYRY) -- its partner on Eylea -- of another treatment option for wet-AMD, a PDGFR-beta antibody. This new compound comes with an upfront $25.5 million payment to Regeneron and could give Regeneron the ability to earn $40 million in option and milestone payments. Although Regeneron's forward P/E over 50 is still very frothy, the simple fact that Eylea remains so dominant, especially with overseas growth still in its infancy, gives me reason to believe it could hold $300.

Are you overlooking this incredible growth opportunity?
Opportunities to get wealthy from a single investment don't come around often, but they do exist, and our chief technology officer believes he's found one. In this free report, Jeremy Phillips shares the single company that he believes could transform not only your portfolio, but your entire life. To learn the identity of this stock for free and see why Jeremy is putting more than $100,000 of his own money into it, all you have to do is click here now.

Fool contributor Sean Williams owns shares of Thompson Creek Metals and Bank of America, and is short shares of Tesla Motors, but has no material interest in any other 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.

The Motley Fool owns shares of, and recommends Tesla Motors and Bank of America. Try any of our Foolish newsletter services free for 30 days. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.