There are ambitious corporate investments, and then there is Masayoshi Son. Whenever I think the artificial-intelligence spending boom has finally reached a number large enough to make everyone involved reconsider their life choices, SoftBank shows up with another zero. This time, SoftBank Group is heading into the high-yield bond market looking to raise more than $11 billion, with the money helping finance its enormous push into artificial intelligence and, more specifically, its increasingly concentrated bet on OpenAI. And when I say “high-yield,” I am using the polite Wall Street terminology. We are talking about junk bonds. Lots of them. SoftBank is marketing approximately $10 billion of dollar-denominated debt along with €1 billion, or roughly $1.1 billion, of euro-denominated bonds. If completed at that size, the transaction would rank among the largest corporate high-yield bond offerings ever. That's impressive. It's also slightly terrifying. Because beneath all the exci...