The $4.2 trillion hole in AI's building plan

$6 trillion is what Bain says it will cost to build the computers and data centres behind AI. Expected software sales of $1.2 trillion to $1.8 trillion leave about $4.2 trillion missing, Bain said in its Sept. 29, 2026 Technology Report. Like a mortgage, how that borrowing is arranged matters for savers and borrowers tied to the debt.