The Numbers Show Silicon Valley Is Already Fading

The construction of large corporate headquarters and skyscrapers often turns out to be a sign of an economic peak. The Empire State Building was planned, and construction began, at the onset of the Great Depression. The Willis Tower, originally known as the Sears Tower, began construction right before the stock market crash of 1973-74. (Soon after, Wal-Mart, which eventually disrupted Sears's business model, began trading as a public company.) The Burj Khalifa in Dubai, currently the tallest building in the world, was under construction as the global financial crisis began in 2008.

That history gives a bit of an ominous feel to the new $5 billion headquarters for Apple in Silicon Valley. The most valuable publicly traded company in the world unveiled its iPhone X earlier this month, with the highest price tag yet -- almost $1,000. So many superlatives. It certainly sounds like peak … something.