The four veteran members of the stock market’s $1 trillion valuation club have something that newcomer Tesla doesn’t have yet: the massive revenues that come with market domination. They also dominate many people’s portfolios: Together, they account for more than 20% of the value of the S&P 500, which means the index-fund-owning masses have a lot riding on their continued success. Here’s what investors should watch going into 2022.

Alphabet

Alphabet

Market cap

$1.95 trillion

Stock return since pre-pandemic high*

92%

Strengths

Alphabet’s Google unit commands about 30% of the digital advertising market, according to eMarketer. That business is a profit-generating machine, with YouTube adding high-octane fuel to its engine.

Threats

Regulators in the U.S. and Europe are pursuing a range of antitrust cases against Alphabet, arguing that the connections between Google’s search and ad businesses are anticompetitive. Alphabet says that its methods are fair and transparent. Still, any court defeat or settlement that changes its business model could ding profits and startle shareholders.

Amazon

Market cap

$1.81 trillion

Stock return since pre-pandemic high

65%

Strengths

The pandemic has only deepened our addiction to e-commerce, where Amazon dominates, and its pioneering cloud-service business remains by far the market leader. Both businesses are inflation-proof.

Threats

Retailers big (Walmart, Target) and small (the many customers of Shopify) are getting better at e-commerce, and more competition could mean more modest growth. Amazon’s shares trade at 70 times earnings (far above the S&P 500 average of 24), and investors may lose some enthusiasm if Amazon’s trajectory flattens out.

Apple

Market cap

$2.64 trillion

Stock return since pre-pandemic high

102%

Strengths

Apple’s ecosystem of higher-end tech products—encompassing iPads, iPhones, and computers, apps, and services like Apple Music—keeps consumers loyal. It also generates great margins: Apple has been the most profitable company in the Fortune 500 for six of the past seven years.

Threats

The global semiconductor shortage is a huge headache for a company that ships as much hardware as Apple. The company said the chip crunch cost it more than $6 billion in lost revenue in the most recent quarter. A court ruling in September, meanwhile, requires Apple to let iPhone developers point consumers to payment options outside its App Store, a move that could harm the store’s profits.

Microsoft

Market cap

$2.55 trillion

Stock return since pre-pandemic high

84%

Strengths

A company once known almost exclusively for Windows and Office has evolved to encompass cloud services (Azure), a thriving gaming platform (Xbox), cybersecurity and A.I. Like Apple, its offerings tend to be “sticky,” with customers coming back regularly to deliver predictable revenue growth.

Threats

Microsoft’s cloud business, its biggest recent success story, faces hefty competition from fellow trillionaires Amazon and Google, among others. And web-based productivity tools continue to shrink Windows’ market share.

*Stock returns from 2/19/20 through 11/22/21; market cap as of 11/22/21.