Advertising growth was the chief driver of tech's blowout quarter, as the economy snapped back from the pandemic and a long-term shift to digital went into overdrive, Sara Fischer reports.

By the numbers: Facebook, Snapchat, Twitter, LinkedIn, YouTube and Google all posted record ad revenue growth rates in earnings reports for 2021's second quarter.

• Facebook and Google grew ad revenues by 55% and 68% year over year, respectively.
• Snapchat and Twitter both nearly doubled ad revenue year over year.
• YouTube brought in a record $7 billion in ad revenue last quarter, more than Snapchat, Twitter and LinkedIn combined.
• Microsoft said LinkedIn surpassed $10 billion in yearly revenue for the first time in its history, largely driven by momentum from digital ads.
• Even Apple said it reached an all-time high in services revenue, which includes advertising.
• Amazon, Etsy, Pinterest and other ad-driven tech giants are all expected to see similar gains when they report earnings in the coming week.

Of note: It's far more common for companies with relatively modest total ad revenues — like Twitter and Snapchat, which both stand at roughly $1 billion for the quarter — to show such fast rates of growth.

• For companies the size of Google ($50.4 billion ad revenue) or Facebook ($28.6 billion ad revenue), it's wild. (See item 2 below.)

Be smart: Three factors drove last quarter's monster growth:

1. Digital transformation: The pandemic expedited the migration of eyeballs and ad dollars to digital platforms. Big Tech firms were uniquely positioned to reap the benefits of that shift.
2. COVID crash: The ad market plummeted during the second quarter of 2020 and then rebounded dramatically beginning late last year. So this year's Q2 shows an extra big leap from last year's.
3. Apple delay: The delayed rollout of Apple's new privacy feature means that tech companies weren't affected by ad-targeting changes as much as they will be in future quarters.

Flashback: A year ago, tech firms warned that ad revenue growth would slow down because of pandemic-related business cutbacks.

• Fears of such headwinds forced tech companies to double down on other digital products, like e-commerce and short-form video.

Those investments are now paying off.

• Facebook said Wednesday that video consumption accounts for nearly half of all engaged time on its platform. It says its TikTok competitor, Reels, is the largest contributor to engagement growth on Instagram.
• YouTube says its TikTok competitor, Shorts, has surpassed 15 billion global daily views, up from the 6.5 billion that it previously announced in March. 

What to watch: Last quarter proved how resilient ad-driven tech firms have been through a period of extreme volatility. But growth rates are unlikely to be this dramatic in the year's second half.

It's harder for a company to grow fast once it's grown big. That's been a law of business physics forever — but, as Felix Salmon reports, today's tech giants are rewriting it.

The big picture: The standard view from Wall Street to Silicon Valley has always been that fast growth is found in startups, while mature companies provide a much more reliable income stream. Today's tech giants, however, are growing at a pace that many entrepreneurs would covet.

By the numbers: As recently as 2017, Apple, Microsoft, Alphabet and Facebook combined were worth less than $2 trillion. Today, Apple and Microsoft are each worth roughly that. The five biggest tech giants (including Amazon) are now collectively worth $9.3 trillion.

• The four companies reporting this week so far generated an astonishing $250 billion in profit just over the past 12 months. Ten years ago, when they all mostly looked identical to how they look today, their profits were less than $58 billion.

Flashback: After the "Nifty Fifty" large-cap stocks imploded in the mid-1970s, Forbes magazine wrote their post-mortem in 1977.

• Investors had gone temporarily insane, wrote the anonymous author, since "no sizable company could possibly be worth over 50 times normal earnings."

Now, consider Microsoft at this point in 2018. It was a very mature and very large company, with trailing earnings of a massive $16.6 billion. At a valuation of almost 50 times earnings, it was worth $809 billion.

• Microsoft easily grew into that valuation over the course of three years during which its core product lineup barely changed.
• Today, its trailing earnings are more than $61 billion, and growing fast. Its market cap is $2.2 trillion, or 35 times its trailing earnings.

Google and Facebook both announced Wednesday that they would require everyone in their offices to be vaccinated against COVID-19.

Meanwhile, Twitter shut down offices in San Francisco and New York that it had only reopened two weeks ago.

Why it matters: The Delta variant's spread is upending corporate plans for a quick and steady resumption of in-office work, and vaccine mandates are one way for companies to put employees at ease and increase their safety.

The big picture: Google and Facebook were some of the first big U.S. companies to send workers home in March 2020.

• This March Google set Sept. 1 as a back-to-the-office deadline, but it has been steadily revising plans as the virus situation has evolved. It's now telling employees they can continue working from home at least through Oct. 18.

Details: In a memo that was also posted online, Google CEO Sundar Pichai said the vaccine mandate "will vary according to local conditions and regulations, and will not apply until vaccines are widely available in your area," per a memo to employees.

• He said there will be "an exceptions process for those who cannot be vaccinated for medical or other protected reasons."

Today is the day everyone can begin buying and selling shares in Robinhood, the trading app that made playing the stock and options market into an alluring game for a new generation of investors.

Driving the news: Robinhood, which is going public on the NASDAQ after raising $1.89 billion in its IPO, has also drawn regulatory and political scrutiny for a variety of business practices, Kia Kokalitcheva reports.

• The company found itself in the crosshairs after users drove up the price of GameStop earlier this year and Robinhood briefly shut down trading in the stock.

The bull case: Robinhood has become synonymous with mobile, no-fee trading of stocks, options and cryptocurrencies. Its business is booming.

• Revenue soared more than 300% between the first quarter of 2020 and 2021, hitting $522 million. Annual revenue in 2020 was $959 million, up from just $277 million in 2019.
• The company claims that over 50% of its users are first-time investors and that its median customer age is just 31 years old.
• It's also benefitting from increased interest in cryptocurrencies, with Robinhood's crypto under custody growing from $414 million at the end of 2019 to $3.53 billion at the end of 2020.

The bear case: The risk factor section of Robinhood's IPO filing is a whopping 75 pages.

• Plenty is boilerplate, but a lot is very specific to Robinhood, which is the subject of class action lawsuits tied to this past winter's meme stock trading frenzy and regulatory lawsuits over alleged securities law violations.
• Robinhood's primary revenue source is from something called payment for order flow, and there's been some political and regulatory movement toward limiting or even abolishing the practice.

Editor's note: This item has been corrected to note that Robinhood will trade on the NASDAQ, not the New York Stock Exchange.

On tap

Amazon earnings this afternoon complete this week's blitz.

Trading places

Shane Arnott, previously of Boeing, joins Palmer Luckey's defense-tech startup Anduril as chief engineer.

ICYMI

• Retailers are deterring theft by using tech to disable stolen devices remotely. (Axios)
• Spotify founder and CEO Daniel Ek spoke to Dan Primack on the Axios Re:Cap podcast about how podcasts are changing, why he's spending big on exclusive shows, and why he thinks Spotify isn't responsible for content from podcasters it pays, like Joe Rogan.

Ina Fried writes from Japan: Many people know about the famous Japanese toilets — with their heated seats, music to help you go and bidets to keep you clean — but their coin laundry is also light years ahead of what we have in the U.S.

For less than $5, a single machine at our hotel can both wash and dry a load of up to 3kg (6.6 pounds) in two hours. You can even set a security code to make sure no one walks off with your clean socks.