Jeff Bezos’ ownership stake in Amazon has fallen below 10% for the first time in the company’s history — marking a milestone in the billionaire’s decades-long relationship with the e-commerce giant he built from a Seattle garage.The Amazon founder disclosed in a Tuesday securities filing that he now holds roughly 9% of the company’s outstanding shares after unloading more than 100 million shares over the past year.A year ago, Bezos controlled about 10.1% of the company, according to regulatory records. When ...