Companies all across America are warning business is slowing down. Here are 6 you should pay close attention to.

Amazon reported quarterly profits and revenue that topped Wall Street's estimates back in February.

But the Jeff Bezos-led company offered investors weak sales guidance, causing at least five analysts to slash their price targets, pointing to slowing trends across some business segments.

Following the report, Morgan Stanley analysts said the fact that Amazon's growth was broadly slowing — though still growing — speaks to how incremental e-commerce growth is becoming "somewhat more difficult and expensive."

Nike shares tumbled Friday after the company's quarterly sales, and North American revenue specifically, just missed expectations.

While robust quarterly profits beat out estimates, investors were focused on the outlook for the rest of the year.

Nike said on Thursday's call with analysts that foreign-exchange pressures would dent revenue growth during its fourth-quarter. The sneaker giant reported 7% revenue growth in North America and a 19% gain in China — both reflecting a quarter-over-quarter slowdown.

Still, the stock is trading within striking distance of its all-time high.

Shake Shack said in its latest quarterly report out in February that it expects flat to slightly higher same-store sales growth this year.

Profits and revenue both topped analysts' expectations, but the burger chain said it expected comparable same-store sales growth of between 0% and 1% for fiscal year 2019.

That included the menu price increases of roughly 1.5% that were put into effect last December.

Caterpillar missed both analysts' profits and guidance expectations in its latest quarterly report.

The industrial giant said it expects full-year profits of $11.75 to $12.75 a share, falling short of the $12.72 that analysts were expecting.

"Our outlook assumes a modest sales increase based on the fundamentals of our diverse end markets as well as the macroeconomic and geopolitical environment," Jim Umpleby, the chairman and CEO, said in a statement.

FedEx shares tumbled earlier this week after the company once again reported quarterly results that fell short of expectations.

The company blamed performance on a slowing global macroeconomic environment.

"Our third quarter financial results were below our expectations and we are focused on initiatives to improve our performance," said Frederick Smith, the company's chairman and CEO, in a statement on Tuesday.