Enthusiasm seems to have waned following a powerful rally that erased much of the pandemic-driven losses for major stock indices. The Dow Jones Industrial Average (DJINDICES:^DJI) was down 0.6% at 12 p.m. EDT Wednesday, undoing some recent gains.

While the economy is reopening across the United States, the possibility of a surge in cases of the novel coronavirus may be spooking investors. Top U.S. infectious disease expert Anthony Fauci recently warned that the pandemic is far from over.

Shares of Boeing (NYSE:BA) underperformed the Dow as a recent rally driven partly by optimism over a recovery in air travel ran into a brick wall of economic reality. Meanwhile, Apple (NASDAQ:AAPL) stock managed to produce a new 52-week high as the company prepares to launch new iPhones later this year.

A plane.

Image source: Getty Images.

Boeing's rally runs up against reality

June has been a good month for Boeing investors so far. Through Monday, Boeing stock had gained a whopping 58% in just over a week. Shares of the troubled airplane manufacturer are still far below their 52-week high, but the rally has erased at least some of those losses.

Boeing stock slumped on Tuesday, and it's down again on Wednesday as the rally appears to be petering out. Shares were trading 5.5% lower in the early afternoon, making Boeing the biggest laggard in the Dow.

While there's some reason to be hopeful that demand for air travel will rebound faster than the most pessimistic estimates, the reality is that Boeing is delivering very few planes. Boeing delivered just four planes in May, down from an already bleak six planes in April, and down 87% from the same period last year. Cancellations totaled 18 planes, including 14 of the still grounded 737 Max.

A scenario that isn't good for Boeing that could play out: Demand for air travel rebounds quickly, but it settles lower than pre-pandemic levels. That could drive the most indebted airlines into bankruptcy, and it could lead to a multi-year period with little demand for new commercial planes.

Boeing raised $25 billion by selling new debt in April, so it has enough liquidity to endure a prolonged period of weak demand. But that additional debt will act as an anchor once the crisis has passed, making the company more fragile, and the stock riskier.

With Wednesday's slump, shares of Boeing are now down about 47% from their 52-week high.

Apple hits new 52-week high

Despite abysmal demand for iPhones over the past few months, shares of Apple carved out a new 52-week high on Wednesday. The stock was up about 2.4% by early afternoon.

U.S. iPhone sales were reportedly down 77% in April, according to data from KeyBanc, as Americans stayed home amid the pandemic. Apple's fiscal second quarter, which ended on March 28, only captured a small portion of the carnage. Global iPhone sales were down just 6.7% year over year.

Apple's fiscal third quarter results are likely to look much worse, although investors may be betting on strong demand for 5G iPhones expected to launch later this year. Delays are possible due to supply chain disruptions, but the stock seems to be pricing in some serious pent-up demand.

One problem with this narrative: The U.S. is now officially in a recession, and there's no telling how bad the economy will be come September, when Apple typically announces new iPhones. While the first-order economic effects of the pandemic – major job losses in industries directly affected, like hospitality and restaurants – are presumably in the rearview mirror, a shock of this magnitude will likely have economic implications for years to come.

Apple stock is riding high, but if the company's new iPhones are met with tepid demand later this year as consumers batten down the hatches, it's hard to imagine the tech stock not taking a hit.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.