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.

The endless rally of 2013 continued today, with a mixture of post-holiday euphoria and an improving jobs picture pushing the broad-based S&P 500 (SNPINDEX:^GSPC) to a fresh all-time high.

No piece of economic data was more critical to today's rally than the initial jobless claims figure for the week ending Dec. 21, which fell by a whopping 42,000 over the previous week to a seasonally adjusted 338,000. You should understand that hiring around the holiday season is often erratic, so seeing a big jump or drop in these figures should come with a grain of salt. However, following a claim jump of 82,000 over the previous couple of weeks, skittish investors who were worried about the jobs market can likely calm down a bit.

With third-quarter GDP rising better than 4% and the unemployment rate at a five-year low, traders seemed perfectly content to push the S&P 500 higher by 8.7 points (0.47%), to close at 1,842.02.

Topping the charts and leading all stocks higher today was small-cap biopharm Inovio Pharmaceuticals (NASDAQ:INO) which gained 20.2% by the end of trading. Inovio develops synthetic vaccines to treat infectious diseases and cancer, so interest in the company has been high throughout the year. Although there was no specific development today pushing the stock higher, recent news has certainly served as a strong catalyst to push shares upward. Hedge fund Moore Capital Management, for example, recently disclosed a new position in Inovio in its quarterly 13F SEC filing. With plenty of near-term catalysts expected in 2014 (i.e., clinical trial results) and a number of pre-clinical success stories, you'll want to keep your eyes on Inovio in the upcoming year.

The other two top performers today -- Navios Maritime (NYSE:NM), up 10.9%, and DryShips (NASDAQ:DRYS), up 12.7% -- both come from the shipping sector and shared something in common with Inovio -- a lack of driving news.

What appears to be pushing both dry-bulk shipping companies higher is the huge rally in the Baltic Dry Index since early August. The latest reading of 2,277 is up nearly 130% in just shy of five months and would portend that higher daily charter rates could be in the offing. Navios Maritime and especially DryShips have been gun-shy about locking in long-term leasing rates at historically low BDI levels, so this new surge in the index could allow these companies to secure longer contracts at better dayrates.

I would, however, strongly suggest you keep in mind two factors with the shipping sector. First, debt is a formidable concern for many of these companies. Navios' approximately $1.2 billion in net debt isn't unmanageable, but DryShips' $4.8 billion in net debt is downright scary! The other factor is that ship overcapacity isn't likely to remedy itself with the retirement of older ships for at least the next couple of years. This means that a rebound in the BDI probably isn't going to be a quick fix for the sector as a whole.

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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