Before Spanx founder Sara Blakely became the youngest self-made female billionaire, she sold fax machines door to door because she needed the money and health insurance.

Now, two decades after Blakely launched the pioneering womenswear company, global investment firm Blackstone is buying a majority stake in Spanx, which is valued at an estimated $1.2 billion in the deal.

In a video posted on Instagram last week, Blakely celebrated the sale with her employees.