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.

Today might not strike you as the most prosperous day for American industry on record, but corporate America has, in some respects, never looked better. Both the Dow and the S&P 500 Index (^GSPC -0.46%) ended at all-time closing highs Tuesday, clearly showing how dramatically Wall Street has rebounded from its recent lows less than five years ago. One needn't possess superhuman powers of deduction to see that Main Street's plight, on the other hand, is very much under way, with the unemployment rate still above 7% and the labor participation rate at the lowest in decades. But with corporate profits in the clouds and the Federal Reserve likely to continue accommodative monetary policies, the S&P 500 Index added 9 points, or 0.6%, to end at 1,771 Tuesday.

That's not to say some stocks in the benchmark index weren't feeling the pain today -- a few of them probably would've been yelling for their mommies Tuesday, had they been sentient beings. Plum Creek Timber (PCL.DL), for instance, slumped 6.6%, even after profits advanced by more than 20% in the quarter. Plum Creek Timber managed to beat expectations on both revenue and earnings in the period, but shareholders were peeved that the company plans to issue an additional 14 million shares to finance an acquisition. Plum Creek also forecast fourth-quarter earnings just below what analysts were looking for.

Goodyear Tire & Rubber (GT -1.59%), our second laggard of the day, is a fine example of how difficult markets can be to please. With shares shedding nearly 6%, you'd think the iconic tire maker had just absentmindedly produced millions of rubber square-shaped tires for an entire quarter. (Not the case, as it turns out.) Goodyear actually saw profits soar 51% from the same quarter a year ago, as the Latin American and North American markets drove the surge in growth. Sales, however, simply didn't impress Wall Street, as they fell by 5% to a pesky $5 billion in the quarter.

Finally, machinery giant Cummins (CMI -0.25%) dropped 5.2% Tuesday; here is one stumble you won't have to scratch your head about. As colleague Rich Smith noted earlier, Cummins underperformed on both earnings and revenue expectations -- a big no-no -- in the most recent quarter. "Oh by the way," the personified Cummins essentially said to its investors, "the fourth quarter won't be so hot, either." This final offense cemented research outfit R.W. Baird's decision to downgrade shares from an "outperform" to a "neutral" rating. This goes to show that analysts don't always have the most realistic expectations for a stock, and while investors would certainly like to see Cummins growing earnings at a clip higher than 0.9%, corrections like today's are necessary every now and then: investors shouldn't have unreasonable expectations for their holdings.