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 hasn't been a blistering beginning to the new year, with the broad-based S&P 500 (SNPINDEX:^GSPC) dipping, albeit modestly, for a third straight session following more mixed economic data at home and weaker-than-anticipated data out of China.

Domestically, an upward revision in November's factory orders to 1.8% from original estimates that pegged this figure at a 0.9% decline is good news. The $498 billion in new orders is an all-time record high, and it would support the idea that the U.S. economy is strengthening and that this momentum may have legs.

On the flipside, December's ISM Services Index dipped to a reading of 53 from 53.9 in December. The drop in this non-manufacturing index could point to weakness in new orders for the service sector in the immediate future, which would almost certainly be bad news for the retail sector.

The deciding factor today, though, was a weak Chinese PMI reading of 50.9 in December, compared with a reading of 52.5 in November. Normally, inflation is the enemy of the consumer, but rapidly decreasing inflationary pressures could bode poorly for China's growth, which has already seen manufacturing data disappoint within the past week. If China's rebound isn't on track, it's going to be difficult to maintain this rally in the U.S.

By days end, the S&P 500 had shed 4.60 points (-0.25%) to close at 1,826.77, and has still yet to log a positive close in 2014.

Topping the charts and leading all stocks to the upside today is China-based online retailer LightInTheBox (NYSE:LITB), which added 20.4% after announcing the acquisition of privately held Seattle-based online clothing retailer Ador. Although financial details of the transaction weren't disclosed, it will, nonetheless, give LightInTheBox its first office in the United States. With a wide variety of products in its catalog, and the company now using this purchase to leverage consumers' love for celebrity outfits (Ador focused on finding outfits fr its customers similar to what celebrities wear), I could see this rebound in LightInTheBox's shares still having legs.

Not too far behind LightInTheBox in the win column was clinical-stage biopharmaceutical company Peregrine Pharmaceuticals (NASDAQ:PPHM), which galloped 14.5% higher following the announcement that lead second-line non-small-cell lung cancer drug bavituximab had gained the coveted fast track designation from the Food and Drug Administration, and that it was initiating its phase 3 study of bavituximab on approximately 600 patients. The fast-track designation could allow bavituximab to reach pharmacy shelves even faster. In mid-stage trials, bavituximab more than doubled median overall survival and overall response rate while delivering a 40% improvement in progression-free survival, but a "hiccup" involving an outside lab contractor left these results questionable in the eyes of shareholders. This phase 3 trial will go a long way to proving Peregrine and bavituximab's credibility.

Finally, sticking within the biopharmaceutical sector, Cell Therapeutics (NASDAQ:CTIC) tacked on 12.7% after receiving a positive final appraisal determination from the National Institute for Health and Care Excellence, or NICE, for its relapsed/refractory aggressive B-cell non-Hodgkin lymphoma drug, Pixuvri. The determination by NICE that the drug its cost-effective will allow U.K. physicians to utilize the only approved treatment for aggressive B-cell NHL once CTI launches the drug in the country in the early spring. While this is welcome news for shareholders, CTI is going to need a lot more than just Pixuvri if it's going to turn a profit. With its history of destroying shareholder value, I'd suggest keeping your distance until CTI's losses narrowing in a big way.