Facebook Inc. wielded user data like a bargaining chip, providing access when that sharing might encourage people to spend more time on the social network -- and imposing strict limits on partners in cases where it saw a potential competitive threat, emails show.

A trove of internal correspondence, published online Dec. 5 by U.K. lawmakers, provide insight into the ways Facebook executives including Chief Executive Officer Mark Zuckerberg treated information posted by users like a commodity that could be harnessed...