Dow Jones, Netflix, and Why Ghosts Say 'Boo'

What is the Dow Jones?

Created in 1896, the Dow Jones Industrial Average is one of the world’s oldest and most widely recognized stock indexes—a measure tracking the stock performance of a selected group of companies (see most recent data).

Originally designed to track America’s leading industrial firms, the Dow has evolved into a cultural and financial shorthand for the health of the US economy. As of 2025, it measures 30 major companies—like McDonald's, Boeing, and Nike—across sectors such as technology, healthcare, finance, and consumer goods. 
 

Unlike most modern indexes, which are weighted by the total value of a company’s shares, the DJIA uses a price-weighted formula—meaning stocks with higher share prices exert more influence, regardless of company size. The DJIA has been updated 59 times since its creation to reflect changes in the US economy (see chart). Companies can be removed if they decline in relevance, merge or are acquired, or no longer represent the sectors the index aims to capture.

... Read our full deep dive on the index here.

Also, check out ... 

> Even iconic companies get dropped from the Dow. (More)

> The theory of market analysis developed by the man behind the Dow Jones index. (More)

> Dow components are chosen by a committee, not a formula. (More)

In partnership with Noom

The Psychology-First Path to Wellness

Quizzes get a bad rap – and we blame high school history class for that. But some quizzes actually do have a purpose (beyond just stressing you out), and this one from Noom is the perfect example. In as little as five minutes, this questionnaire will help you:

> Identify your health, sleep, stress management, or fitness goals

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> Create a tailored timeline for reaching your goals

The quiz is just one part of Noom’s science-backed, holistic approach to your health goals. Their program focuses on making behavioral changes to help improve your sleep, nutrition, stress, and more – all while prioritizing sustainable, long-term results. In fact, Noom users report a 45% reduction in overall healthcare costs after 6 months with Noom.* That’s proof in the pudding.

Noom has helped millions of people lead healthier lives. Ready to take a new approach to your health? Take this 5-minute quiz – 1440 readers can try Noom free for 14 days.

*Based on a 6-month retrospective matched case-control analysis of 723 Noom users and 723 non-Noom members based on Aetna data for a Noom Health Customer.

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Climatology, explained
Climatology is the science of climate, or the study of long-term atmospheric conditions across Earth. Unlike meteorology, which uses data to predict weather over several days, climate science focuses on identifying patterns across 55 essential climate variables over periods of 30 or more years. These patterns help climatologists better understand the interactions between Earth’s systems and refine computational models to predict future phenomena.

Climate variable data, including temperature via the thermometer and air pressure via the barometer, have been directly collected and recorded since the 1600s. Data from before this instrumentation was invented can be obtained by analyzing climate proxies—materials that preserve past climate conditions.
 

This data is used to test the accuracy of climate models—created by applying the laws of physics to Earth's systems—before they are run on supercomputers to project future conditions.

... Read our full explainer on climatology here.

Also, check out ... 

> Earth has shifted between extreme warming and cooling periods for 500 million years. (More)

> Climate models have predicted sea level change almost perfectly for 30 years. (More)

> Layers in Earth's sediment hold clues to Earth's climate. (More)

Netflix, 101
Netflix is the dominant streaming platform today, with more than 300 million subscribers. It pioneered the "bingeable" format after starting as a DVD rental company and now produces and releases hundreds of original shows and movies each year.

The company was founded by Reed Hastings and Marc Randolph and spent its first decade oscillating between survival and growth. It survived the dot-com bubble, went public in 2002, and emerged victorious in fierce competition with Blockbuster. As high-speed internet became pervasive, the company began streaming content directly to subscribers, letting them watch movies and TV shows instantly instead of waiting for DVDs by mail.

The company began offering original content in 2013, and launched its first prestige drama with “House of Cards.” Hit franchises that followed included “Stranger Things” and “The Crown,” among many others.

... Read our full write-up on the streamer here.

Also, check out ... 

> How binge-watching was the result of a competition. (More)

> The complex infrastructure initiated by pressing "play" on Netflix. (More)

> Why Netflix's movies seem so similar. (More)

Best of the Week

We added 131 resources this week to our knowledge collective—here are some of our favorites.

How candymaker Haribo focuses on gummies to simplify production.

Who pays for science? Mostly private businesses and the federal government.

How did the Silk Road actually work?

Ghosts didn't say "boo" until the 19th century. 

Were Greek boxers ripped? And other fact-checks about the ancient world.

It took the inventor of the Rubik's Cube a month to solve the puzzle. 

The fabulous prison escapes of Japan's "Harry Houdini," Yoshie Shiratori.

There may be 2 billion people asleep right now on Earth.

Toronto has 18 miles of underground pedestrian tunnels. 

What's the difference between capitalism and socialism?

An epic (four-hour) listen on Google's AI innovations—and playing catch-up with OpenAI.

The technical name for goosebumps is "piloerection." 

Economics progresses from ideas, according to Nobel winner Joel Mokyr.

Simulate an asteroid and measure its impact while studying defense scenarios.

The 31 best science fiction films of all time. 

In partnership with Noom

'Almost 200 Pounds Lost'

You read that right – Noom, the leader in sustainable health management, helped Noomer Steve H lose almost 200 pounds*. “I found my why. My health, my future, and my family … are my daily motivation.”

And guess what? Steve is far from alone. Millions of people have used Noom to lose weight, keep it off, and improve their overall health thanks to new additions like Noom’s Healthy Aging & Metabolism Course*. Whether you’re looking to feel better, hit your goals, or simply need that little oomph that comes from custom plans and coaching, Noom has you covered. Claim your FREE 14-day trial right here.

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More from 1440

Historybook: British Gen. Charles Cornwallis surrenders at Yorktown, effectively ending the Revolutionary War (1781); John Jay becomes first US chief justice (1789); Actor and director Jon Favreau born (1966); Black Monday stock market crash; Dow Jones drops 22.6% in one day (1987).