Turns out that the one trillion Dollars which the big tech companies (Apple, Google, Amazon...) hold in their offshore accounts are mostly in bonds. By that, these companies have become shadow banks, keeping alive other 'zombie' companies that otherwise would run of credit/go out of business.
The author compares it to the subprime crisis and sees a similar systemic risk for the world economy, now with the tech giants being the corporations that are "too big to fail".