SoftBank Left Millions on the Table to Engineer a Win for Masayoshi Son

(Bloomberg) — Masayoshi Son was determined to turn the tide.

Most Read from Bloomberg

His record on tech investing had taken a drubbing after SoftBank Group Corp.’s Vision Fund lost $32 billion in a year on flameouts like WeWork and DoorDash Inc. So as he and other top executives met with bankers to plot this week’s initial public offering for Arm Holdings Plc, the focus was making sure the sale would go off without a hitch.

They didn’t want any last-minute hiccups with buyers pulling…