The sale of the company, whose production slate has included programming such as the HBO drama "Big Little Lies," and while will makes Witherspoon one of the wealthiest people in Hollywood is "part of a plan to build an independent entertainment company for Hollywood's streaming era" with an emphasis on women's content. 

According to the Journal, the as-yet-unnamed media venture Blackstone is backing will be run by former Walt Disney executives Kevin Mayer and Tom Staggs. Hello Sunshine will be its first acquisition. Witherspoon and Hello Sunshine CEO Sarah Harden will join the board of the new company and will continue to operate Hello Sunshine.

As part of the deal, Blackstone will spend more than $500 million in cash to purchase shares from existing Hello Sunshine investors, including AT&T and Emerson Collective, WSJ sources said. Witherspoon and some Hello Sunshine executives and investors will also roll over the remaining equity into ownership stakes in the new company Blackstone is forming.