Amid all the hyperventilating about eye-popping A.I. company valuations and the seeming insanity of the current investment cycle, old Wall Street hands might feel something tickling in the back of their brain—a memory from the dawn of the internet age, when a group of buzzy companies built the fiber-optic network carrying trillions of bits and bytes across the country that we now take for granted. Needless to say, those internet infrastructure companies were a huge hit on Wall Street. In 1998, Global Crossing went public at a valuation of around $5 billion, and rocketed to a peak valuation of around $50 billion in 1999 and early 2000. In 1996, McLeod USA went public at a valuation of roughly $1 billion, and three years later, my friends at Forstmann Little, the now-defunct buyout firm, made a $1 billion investment in the company in exchange for a 12 percent stake at a roughly $8 billion valuation. By the first quarter of 2000, McLeod’s valuation peaked at around $27 billion.