Amazon's big secret: Prime has nearly 70 million members, Bernstein analyst says

An employee stacks items to be shipped at the fulfillment center in Phoenix, Arizona.
David Paul Morris | Bloomberg | Getty Images

A top Wall Street firm did a deep-dive analysis on the size of Amazon's Prime subscription service, a closely held secret by the e-commerce giant.

"Prime is an essential part of Amazon's retail business," Bernstein's Carlos Kirjner wrote in a note to clients Thursday. "Prime matters most because Prime users likely buy across more categories, more frequently, and we suspect are increasingly loyal to Amazon because of the convenience and benefits provided by the Prime service."

Kirjner has an outperform rating on Amazon with a 12-month target of $1,000 a share, representing 39 percent upside from Wednesday's close.

Using survey data from 1,700 households and after analyzing the unearned revenue trend in Amazon's financial statements, the firm estimates there were 58 to 69 million global Amazon Prime subscribers at the end of 2015.

Some other key findings about Prime from the report: