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 achieving another record high yesterday, stocks opened lower this morning, with the S&P 500, and the narrower, price-weighted Dow Jones Industrial Average (DJINDICES:^DJI), down 0.6% and 0.4%, respectively, as of 10:07 a.m. EDT. In trying to explain the drop, Reuters points to "concern over tightening financial conditions in China and weakness in European banks." I think that, given the market's strength post-government shutdown in the face of mixed corporate earnings, as well as yesterday's weak employment data, any excuse will do for some sort of pullback at this stage.

Perhaps the global economy isn't going off a cliff, after all. This morning's third-quarter results from Dow component Boeing (NYSE:BA) indicate that airline carriers are still in the market for commercial aircraft.

A 15% increase in commercial sales and a 14% increase in deliveries to 170 aircraft boosted Boeing's revenue by 11% year on year, to $22.1 billion, a bit ahead of the $21.7 billion Wall Street was expecting. On the bottom line, core earnings per share rose to $1.80 – 16% above the $1.55 consensus estimate. Boeing now expects full-year earnings of $6.50 to $6.65 per share, up from $6.20 to $6.40. (The company introduced "core earnings," which are adjusted for changes in pension costs due to market fluctuations, in January.)

By comparison, with its commercial activity, Boeing's defense business disappointed, with a mere 3% increase in revenues. Mind you, in an environment in which the federal defense budget is contracting, that's hardly a disastrous result.

Investors are rewarding the stock for this morning's report with a 5.5% adding to an extraordinary run in a year that had the potential to go very differently when Boeing's flagship Dreamliner experienced a serious problem with its lithium ion batteries that ultimately saw the fleet temporarily grounded. Year to date, Boeing's shares are up nearly 70%, far outpacing the broad market and the Dow:

BA Chart

BA data by YCharts.

That sort of rapid price appreciation raises the question of whether Boeing's stock valuation has become stretched. As of yesterday's close, the stock was trading at 18.3 times estimated earnings per share for the next 12 months, against 14.9 for the S&P 500. Boeing has a terrific franchise in a duopoly market, so it deserves a premium valuation over the broad market, but the current premium is beginning to look a bit rich (not to mention that the broad market itself is likely no better than fairly valued, at this stage.)

Point, counterpoint: Another Dow component, Caterpillar (NYSE:CAT), offered a different perspective on the global economy with its third-quarter results. The world's leading manufacturer of construction equipment missed the $1.67 earnings-per-share consensus estimate, posting $1.45, instead, down from $2.54 in the year-ago period. That prompted the company to revise its full-year guidance to $5.50 in earnings per share on sales of about $55 billion, down from $6.50 per share on sales of $56 billion to $58 billion. The culprit is the company's mining equipment activity -- typically its most profitable -- which has suffered a cutback from mining customers worldwide.

The market is not receiving the news well; Caterpillar shares are down 5.7% at the time of writing.

Fool contributor Alex Dumortier, CFA has no position in any stocks mentioned; you can follow him on Twitter @longrunreturns. The Motley Fool has no position in any of the stocks mentioned. Try any of our Foolish newsletter services free for 30 days. We Fools may not 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.