This is a tricky time for investors. September's steep sell-off has created some bargains, but the market's rout may not have run its full course yet, and not even the bluest of blue chip stocks have been immune to this uncertainty.

On balance though, if the sheer scope of the market's recent weakness is the only reason you're interested in a particular stock -- even a Dow stock -- that's probably not good enough. Those Dow Jones Industrial names that have taken the steepest plunges did so for reasons that go well beyond the temporary havoc being created by the COVID-19 pandemic.

Man in suit standing on falling chart, watching it move lower

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The DJIA's biggest losers

For the record, the Dow's three biggest losers for the past month are also its biggest losers for the year: Boeing (NYSE:BA), Walgreens Boots Alliance (NASDAQ:WBA) -- you know it better as just Walgreens -- and Chevron (NYSE:CVX). They're down 53%, 40%, and 40% year to date, respectively, thanks in part to tumbles of 14%, 12%, and 17% over the course of the past month.

It would be easy to chalk those declines up to the tough, coronavirus-impacted environment, and, to be sure, the pandemic is part of the problem for all of these companies. By and large, however, their shares are deep in the red for 2020 mostly because each business has hit the proverbial wall.

To fully appreciate the whys behind the weaknesses though, one has to go all the way back to the beginning of the current growth cycle. That's 2009, when the U.S. led the world out of the subprime mortgage meltdown that it had led it into a couple of years prior. That economic expansion was still going 11 years later, and so was the corresponding bull market. Both obliterated time-based records.

That was not a normal growth period, though -- it was prolonged past its shelf life in an unhealthy way. Benchmark interest rates were held at rock-bottom levels for the better part of the decade, and mere suggestions that they could be lifted back to more normal levels were met with protests in the form of stock market setbacks... even if those persistently low rates were doing more long-term damage than short-term good.

Expansions aren't meant to last quite that long, however, and our recent one has left Walgreens, Chevron, Boeing, and plenty of other companies of their kind struggling to continue growing without the benefit of coming out of a serious sell-off. See, those painful declines act as a reset of sorts  -- and investor expectations are often among the things that get reset.

In simpler terms, we're overdue for a bear market and an economic contraction. Some companies are more overdue for one than others.

A convergence of factors

That said, one must understand that certain sorts of companies aren't struggling just because the growth phase went on for too long. That cycle also overlapped with societal and technological paradigm shifts.

Take Boeing, for example. Its new 737 MAX jets were meant to capitalize on growing demand for air travel coupled with heightened demand from airlines for fuel efficiency. As of last year, Boeing believed the air travel market would more than double in 20 years, while the technology that allowed it to make the 737 MAX up to 20% more fuel efficient than its predecessors hasn't existed until now. Boeing needed the latter to take advantage of the former in a way that would satisfy investors looking for the sort of growth they'd seen coming out of 2009. It now appears Boeing pushed the envelope a little too much.

For Walgreens, market saturation has become a challenge, but that's hardly the only one. Years of unchecked price growth have finally caught up with both the pharmaceutical and retail pharmacy industries. Amazon waded into those waters with its acquisition of online pharmacy PillPack, but governments are increasingly getting involved too, attempting to better police an industry that failed police itself amid its quest for more growth. Walgreens has shifted toward becoming a more holistic, integrated healthcare company by adding clinics to its stores, but that effort has not been a game-changing success. Now Walmart is now wading into the same waters.

As for Chevron, the oil and gas market may never be the same again now that cleaner, greener alternative energy sources are viable.

You get the idea. After an 11-year growth phase, a lot of companies are running out of good ways to grow. The older and less-techy a company is, the tougher the challenge.

Look for the real reason

None of this is to suggest that old-school names can't have second acts in this stage of the economic cycle. For example, Procter & Gamble has reinvented itself over the course of the past five years. It now knows it has to capitalize on digital data to sell its products, and hire more outsiders in key positions if it wants to remain relevant.

If Dow Jones stocks like Boeing or Chevron haven't been able to manage similar reinventions yet though, they probably won't be able to do so until a major, cyclical contraction forces them to rethink... everything.

Bottom line? If a blue chip is down in a big way right now, it's not mere bad luck. It's down for a reason.