Last month was a much-needed win for the stock market. When all was said and done the Dow Jones Industrial Average (^DJI -0.28%) gained nearly 9% in November, reversing a nasty downtrend and reaching a new multi-month high in the process.

Not every Dow stock followed suit, though. A handful of its components managed to log a loss last month.

Savvy investors know these pullbacks might be a buying opportunity. They also know, however, this weakness may only be part of a much bigger sell-off. Here's what you need to know about the Dow's worst three performers last month.

The Dow's biggest November losers

Cutting straight to the chase, November's biggest losers among the Dow's 30 holdings are Cisco Systems (CSCO -0.22%), Walgreens Boots Alliance (WBA 1.06%), and Walmart (WMT 0.42%). They were surprising laggards given these companies' statures. Cisco led the way with a tumble of a little more than 7%, Walgreens fell 5.4%, while Walmart slipped just a little less than 5%.

CSCO Chart

CSCO data by YCharts

What went wrong?

For Walmart, most of its loss came on the heels of the release of its fiscal third-quarter numbers (for the period ending Oct. 27). Although sales and earnings were both up year over year and both better than expected, management rang alarm bells for the quarter now underway.

Specifically, CFO John David Rainey noted that sales had been "somewhat uneven" in the prior couple of months, suggesting that inflation and higher interest rates have finally caught up with consumers. Guidance for the full year was also lackluster. Walmart believes it will earn between $6.40 and $6.48 per share in fiscal 2024, versus analysts' consensus of $6.50.

Shares of networking technology giant Cisco fell the same day for largely the same reason. That is, although sales of $14.7 billion and per-share earnings of $1.11 for the three-month stretch in question were both up year over year (and both better than expected), guidance for the quarter ending in January was disappointing.

The company's calling for a 13% quarter-to-quarter decline in revenue because, as CEO Chuck Robbins explains, "After three quarters of exceptionally strong product delivery, our customers are now focused on installing and implementing these unprecedented levels of products."

As for Walgreens, although it would be easy to link its pharmacists' walkout (in protest of their difficult working conditions) in late-October to last month's loss, the two aren't connected much, if at all. Rather, Walgreens shares simply extended a sell-off that's been underway since 2015 due to the ongoing deterioration of the company's health. Indeed, the stock reached a multi-decade low last month on a combination of concerns about theft, a dividend cut, management turnover, layoffs, and labor headaches, just to name a few.

Time to buy?

The question remains -- are any or all of these discounted stocks a buy now following (and because of) their November setbacks?

It's tempting, to be sure. Investors are generally encouraged to step into good stocks while they're "on sale." And, by virtue of being a constituent of the Dow Jones Industrial Average, these three names are arguably within the upper echelon of prospective stock picks.

This line of thinking, however, looks past one of the more important tenets of successful investing. That is, one month's performance doesn't really mean much in the grand scheme of things. The bigger question is still whether or not a particular company is worth owning at any price.

And that's why November's Dow laggards are a mixed bag now. Some of them are worth stepping into here, while others aren't.

Walgreens Boots Alliance is clearly a name best avoided for the time being. Although its shares are priced at a dirt-cheap forward-looking price-to-earnings ratio of 6 and its dividend yield is a sky-high 9.6%, nothing about this company's results is guaranteed anymore. It could take several more years to undo the damage it's done to itself, including the 2014 merger of Walgreens and Boots Alliance (that's now potentially on its way to being undone) and last year's acquisition of primary care and home care company CareCentrix.

Expanding your reach within a sector generally makes sense on paper. Even companies within the same business sector, however, don't always mesh well in the real world. In the meantime the retailer remains highly vulnerable to organized shoplifting, its relationship with its pharmacists is tense, and a new CEO just took the helm. All of these are liabilities weighing on the stock.

Walmart's a slightly different story. The stock's not a buy right now not because the retailer is performing poorly, but because shares have become so expensive thanks to the 30% run-up from last March's low. Even with the recent pullback, the stock's trading at a trailing price-to-earnings ratio of more than 25. That's pretty rich by this ticker's historical standards. This is a case where you may be best served by holding out for a better price. The company will almost certainly do its part -- growing -- in the meantime.

The only name of the three in question that's a resounding buy right now is Cisco.

Simply put, CEO Chuck Robbins is right. Cisco sales have been well up since the latter part of last year as enterprises finally began the upgrades of their networking hardware that had been put on hold during the COVID-19 pandemic. They don't need more new hardware just yet.

But this headwind was already being priced in. Thanks to last month's sell-off Cisco stock is down 25% from its late-2021 high, and back to where it was trading all the way back in 2019 despite plenty of profits still being produced during this period.

CSCO Revenue (Quarterly) Chart

CSCO Revenue (Quarterly) data by YCharts

These earnings aren't likely to be disrupted anytime soon, particularly now that Cisco is also a serious software company. Its recurring, subscription-based software sales now stand at an annualized rate of $24.5 billion, with even more software revenue than that already lined up. For the sake of comparison, the company's done about $58 billion worth of business over the course of the past four reported quarters.

Bolstering the bullish argument here is Cisco stock's valuation. It's an unusually cheap technology stock priced at only 14 times this year's expected per-share earnings of $3.53. It's even more unusual in that this technology name doesn't just pay a dividend, but pays a sizable one translating into a healthy yield of 3.2%.

The bigger lesson here, of course, is understanding that when it comes to a stock's performance there's always more to the story. Your job as an investor is finding out what the rest of that story is.