The Dow Jones Industrial Average (DJINDICES:^DJI) by midafternoon was trading 23 points lower, or 0.14%, on a day with no major economic news releases. Investors are still wary about situations developing abroad, and news of two Ukrainian fighter jets being shot down Wednesday only added to tensions in the region and caution on the markets. Strong results from Apple and Microsoft, though, are helping the S&P 500 flirt with record highs during intraday trading.

The biggest loser in the Dow index today is Boeing (NYSE:BA), which traded 2.4% lower this afternoon after it delivered a largely upbeat second-quarter earnings report.

At first glance, Boeing's second quarter appears incredibly strong. Despite a meager 1% gain in top-line revenue, up to $22 billion, its net earnings and earnings per share jumped a staggering 52% and 59%, respectively -- and those are generally accepted accounting principles numbers. Boeing's earnings per share hit $2.24 in the second quarter, compared to $1.41 last year.

Source: Boeing.

However, it should be noted that those earnings were substantially aided by two tax benefits of $116 million and $408 million in the quarter. With those benefits accounted for, Boeing management increased its full-year core EPS guidance by $0.75, to a range of $7.90 to $8.10.

Boeing also delivered 181 commercial aircraft in the second quarter, chalking up record deliveries for both the 737 and 787. Boeing's commercial aircraft operating margin rose to 10.8%, though its defense, space, and security operating margin fell from 9.5% in last year's second quarter to 7.5% in the just-completed quarter. That's where we get into one issue investors have with Boeing's second quarter.

The company was forced to take a $272 million after-tax charge for additional costs of engineering and systems installation work for its KC-46A military tanker program. That charge was the equivalent of $0.37 per share and sent Boeing's defense operating margin plunging by 240 basis points in the second quarter.

"To us it is worrying that Boeing is booking a charge of this magnitude at a relatively early stage in this long-term program, particularly given recent assurances from management that everything was going to plan," RBC Capital Markets analyst Robert Stallard stated in a message to clients, according to the Chicago Tribune.

In other Dow news, Caterpillar (NYSE:CAT) is gearing up to release its second-quarter earnings Thursday. If recent sales are any indication, the heavy-machinery manufacturer will have a rough time on its top-line performance.

Source: Motley Fool Flickr. 

Caterpillar's worldwide machine retail sales were down 10% for the rolling three-month period ending in June. The figure was dragged down by yet another poor performance in Caterpillar's Asia-Pacific region, which fell 30%.

The biggest warning sign is coming from Caterpillar's energy and transportation retail sales, which had posted sales increases until May. The three-month rolling sales data declined by 3% in that month, and in June that worsened to a 10% slide. That leaves Caterpillar's construction industries business as the only retail segment posting sales increases.

While revenue will be an issue tomorrow for Caterpillar, the company has proven that it can reduce costs significantly to aid its bottom line -- and that's something investors will key on when the earnings report is released. Another factor that investors must watch is Caterpillar's cash flow. Despite rough economic and business conditions, Caterpillar in 2012 and 2013 produced its best two years of cash flow in company history.

However, any slip in that situation would be a huge blow to investors enjoying Caterpillar's cash flow being dished back to shareholders through increased dividends and share buybacks. 

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.