For more than 125 years, the Dow Jones Industrial Average (^DJI 0.01%) has been a barometer of the stock market's health.

Though it began as a 12-company index back in May 1896, it's now comprised of 30 highly profitable, multinational companies from a broad spectrum of sectors and industries. While the Dow Jones is itself a flawed index -- it's share price-weighted, rather than market cap-weighted -- it nevertheless continues to motor higher over time, and therefore draws plenty of attention from Wall Street and investors.

Among its 30 components are two Dow stocks investors can buy hand over fist in the fourth quarter, along with one widely held company that might be best off avoided to end the year.

An American flag draped over the New York Stock Exchange, with the Wall St. street sign in the foreground.

Image source: Getty Images.

Buy this Dow stock: Salesforce

If there's one Dow stock I'd strongly encourage investors to dig into in the fourth quarter, and well beyond for that matter, it's cloud-based customer relationship management (CRM) software solutions provider (CRM -2.25%).

Without getting overly technical, CRM software is used by consumer-facing businesses to enhance existing customer relationships and boost sales. Beyond just logging and accessing customer data in real-time, it can be used to oversee online marketing campaigns and run predictive analyses to determine which customers might be the likeliest to purchase new products or services. While the service industry has long been the most-logical purveyor of CRM solutions, we're witnessing nontraditional sectors and industries adopting it.

Cloud-based CRM software sales are expected to grow by an annualized double-digit percentage through at least mid-decade, and Salesforce finds itself at the top of the mountain in this high-growth trend. When the curtain closed on 2020, Salesforce was responsible for 19.5% of all global CRM spending, according to IDC. By comparison, the No.'s 2 through 5 in worldwide share didn't even add up to Salesforce's share of the landscape.  While anything is possible in the tech space, this market share lead looks practically insurmountable for the foreseeable future.

CEO Marc Benioff also deserves heaps of praise for successfully executing a number of earnings-accretive acquisitions. The buyouts of MuleSoft, Tableau, and Slack Technologies have all expanded the Salesforce ecosystem and broadened its appeal to the small-and-medium-sized businesses that make it tick.

Between organic growth potential and a steady diet of acquisitions, Benioff is forecasting $50 billion in full-year sales by fiscal 2026. That'd be up from a reported $21.3 billion in fiscal 2021. Mega-cap stocks rarely grow at such speed, which is why Salesforce is such an intriguing buy for the fourth quarter.

A smiling pharmacist holding a prescription bottle and speaking with a customer.

Image source: Getty Images.

Buy this Dow stock: Walgreens Boots Alliance

A second Dow stock to buy hand over fist in the fourth quarter is pharmacy chain Walgreens Boots Alliance (WBA 0.50%).

Generally, healthcare stocks are impervious to economic hiccups. Since we don't get to choose when we get sick or what ailment(s) we develop, there's a relatively constant demand for drugs, devices, and healthcare services in any economic environment. Pharmacy chains like Walgreens proved the exception to this rule during the pandemic. Since pharmacies are reliant on foot traffic into their stores, the coronavirus put a financial hurting on the entire industry. The good news, though, is this short-term pain is now in the rearview mirror.

What should drive Walgreens' valuation higher is the multipoint turnaround plan that was put into motion more than a year ago. As you might expect, management is working on improving overall operating efficiency, which means cutting costs where it makes sense to do so. By the end of fiscal 2022, Walgreens Boots Alliance should be recognizing annual cost-savings of more than $2 billion.

However, the company has been spending aggressively in other areas. In particular, there's a big focus on digitization. The pandemic was a stern reminder that direct-to-consumer sales need to be a focus, even for an industry that's long relied on its brick-and-mortar locations to drive results. Despite accounting for only a small percentage of total sales, online revenue can be a consistent double-digit growth opportunity moving forward.

Also, don't overlook the July 2020 announcement that Walgreens is partnering with VillageMD to open up to 700 full-service clinics co-located in Walgreens' stores in over 30 U.S. markets. The key differentiator here is "full-service" clinics. With physician-staffed clinics, the expectation is this move will draw in repeat business and kick-start growth opportunities for Walgreens' higher-margin pharmacy.

With a forward price-to-earnings ratio of about 9 and a 4.1% yield, Walgreens Boots Alliance is the value stock you don't want to pass up in Q4.

A person holding up a brand-new iPhone box in front of an Apple store during a launch event.

Image source: Apple.

Avoid this Dow stock: Apple

On the other hand, one widely owned Dow stock that might be best avoided in the fourth quarter is innovation kingpin Apple (AAPL 1.66%). Keep in mind that when I say "avoid," I'm not suggesting folks sell their existing shares in the company. Rather, I foresee Apple encountering a handful of short-term headwinds that could temporarily weigh on its valuation.

As many of you know, Apple does a lot of things right. It's no fluke that it's the most-valuable publicly traded company. Apple has exceptionally strong global brand recognition, and its iPhone is the most-popular smartphone purchased in the United States. If you need further evidence of Apple's lure, just take a gander at the lines wrapping around Apple's stores anytime a new product makes its debut.

However, the world's most-valuable company is also up against some extremely difficult year-over-year comps for its top-selling product, the iPhone. Last year, Apple introduced its first 5G-capable smartphone, and the device flew off store shelves quicker than Wall Street could blink. The company generated record sales from its flagship product amid consumers' desire to upgrade their devices to take advantage of faster download speeds.

The recently unveiled iPhone 13 only offered modest changes from its predecessor. While there are new colors to choose from, along with a faster processing chip and a higher-quality camera, the leap from iPhone 12 to iPhone 13 isn't nearly as groundbreaking as what we saw last year.  Apple is probably going to have a very hard time meeting or surpassing last year's iPhone sales figures.

The other issue is the growing likelihood that Democrats on Capitol Hill will pass a large infrastructure bill that'll increase peak marginal corporate income tax rates. Currently peaking at 21%, the corporate income tax rate is expected to land anywhere between 25% and 28% to pay for the ambitious infrastructure bill. Normally, a modestly higher corporate tax rate could be swept under the rug. But with Apple's earnings per share expected to be virtually stagnant in fiscal 2022, any tax reform could send its bottom line into reverse. Since Apple isn't particularly inexpensive, a lack of earnings growth could weigh on its valuation.