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

The market has stepped off a cliff today as the Dow Jones Industrial Average (^DJI 0.06%) posts yet another triple-digit plunge in a young year that's been marked with them. As of 2 p.m. EST, the Dow is down more than 266 points, about 1.7%, after the Institute for Supply Management posted a weaker than expected Purchasing Managers Index report on American manufacturing for January. The market's "fear index," the CBOE Volatility Index (^VIX -1.15%) or VIX, has jumped more than 12% today, and among stocks on the Dow only Pfizer (PFE -0.12%) has managed to stave off losses. Let's catch up on what you need to know.

What to make of the PMI's big drop
The closely watched PMI shed 5.2 percentage points in dropping from December's mark of 56.5 to January's reading of 51.3. Any reading above 50 means American manufacturing is still expanding, but the PMI's growth has fallen off pace and is much closer to dipping back into contractionary territory. The big drop's sparked investor fears and sent the VIX rocketing above the 20-point mark today, making for a 42% gain in the volatility index in just the past three months.

China's own PMI also fell for January, adding to the market's jitters today as investors digest slowing growth in manufacturing for the world's two largest economies. But should you really be nervous about the PMI's big drop and the effects it's had on the market today?

True, there are some worrying signs in the reading. Manufacturing order backlogs fell into contraction in January, while production, new orders, and even employment all saw growth slow. However, prices continued to pick up at a brisk pace, with a 7 percentage point gain, and the sign that customer inventories remain too low is a hopeful indicator that manufacturers can bump up orders in the future.

Perhaps most notably, multiple respondents polled by the ISM reported that unusually cold weather hampered shipping in the first month of the year. Nowhere has that been more evident today on the markets than in the auto industry, as Ford (F 0.17%) reported that U.S. sales in January slumped 7% year over year thanks largely to the frozen temperatures. Ford's stock has plunged 2.6% today as a result of the bad sales numbers, but with the company citing snow and the freeze for hampering car deliveries and keeping customers away from dealerships, there's plenty of reason to believe that February will see improvement -- especially considering the strong growth American manufacturing has seen recently up until this past month.

Around the Dow, Pfizer has posted the lone gains of the day, with the Big Pharma stock up 1.6% in midafternoon Pfizer's developmental breast cancer therapy palbociclib hit the primary endpoints of a midstage study, according to the company. Analysts have pegged potential peak annual sales at up to $5 billion for palbociclib, so the drug's success in the trial is a huge deal for Pfizer and its investors, particularly as the company looks to rally around its pipeline and recently approved up-and-coming drugs like blood thinner Eliquis. These produces are especially key in the wake of the patent expiration of former top seller Lipitor which took a sledgehammer to Pfizer's sales last year.