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.

After yesterday's drop of more than 325 points for the Dow Jones Industrials (^DJI 0.32%), investors were ready for a respite, and today's 72-point gain gave them at least some comfort from what has been a terrible beginning to the year. Yet even though pharma giants Merck (MRK -0.13%) and Pfizer (PFE -0.60%) joined chemical company DuPont (DD) in leading the Dow higher Tuesday, it's far from clear whether the Dow has actually finished its downward move to begin 2014.

Strength from pharmaceutical stocks Pfizer and Merck, both of which rose 2.75% today, has come from a number of corners. First, declining bond yields have helped support their share prices, as many investors look at their relatively low growth and high dividend yields as making the stocks more like bond substitutes than legitimate growth candidates.

Yet the two companies also have opportunities to streamline their operations. Merck earned an upgrade from analysts at SunTrust today, who argued that the combination of cost cutting, more favorable drug development, and smart internal corporate restructuring efforts could boost shares in the near future. Analysts at Jefferies cited nearly exactly the same factors in upgrading Pfizer, also including the anticipated fast-track approval process and launch of the company's palbociclib breast-cancer treatment by the end of the year.

Meanwhile, DuPont gained 2.7% despite the resignation of chief marketing and sales officer Scott Coleman this morning. There's no obvious reason to think that Coleman's departure was linked to DuPont's evolving strategy to emphasize its agricultural sector over its traditional chemicals business, but aligning top executives to move the company forward in the direction of higher margins will be critical for the company's future success. DuPont's restructuring strategy has plenty of potential to bring profit growth, but it will take time for the company to realize that full potential.

Long-term investors shouldn't get bogged down in whether today's smaller gains compared to yesterday's bigger losses imply that further declines are likely. Finding an investment strategy that works regardless of whether stocks move up or down in the next day or week is essential to keep yourself from becoming an emotional wreck in the wake of rising volatility.