In spite of the attractiveness of fake news stories, most people are reluctant to share them. Why? Four pre-registered experiments ( N = 3,656) suggest that sharing fake news hurt one’s reputation in a way that is difficult to fix, even for politically congruent fake news. The decrease in trust a source (media outlet or individual) suffers when sharing one fake news story against a background of real news is larger than the increase in trust a source enjoys when sharing one real news story against a background of fake news. A comparison with real-world media outlets showed that only sources sharing no fake news at all had similar trust ratings to mainstream media. Finally, we found that the majority of people declare they would have to be paid to share fake news, even when the news is politically congruent, and more so when their reputation is at stake.