Amazon.com Inc. AMZN, +3.86% said Thursday it has signed an agreement to acquire One Medical, a primary care organization that operates under 1Life Healthcare Inc. ONEM, +3.25% , for $18 a share in cash, or $3.9 billion including debt. "We think health care is high on the list of experiences that need reinvention," Neil Lindsay, senior vice president of Amazon Health Services said in a statement.