A webpage that masqueraded as a New York Times article and claimed that Senator Elizabeth Warren of Massachusetts had endorsed Bernie Sanders for president circulated widely on social media on Monday.

The fake news article, which mimicked The Times’s typefaces and design and included the bylines of two of the newspaper’s political reporters, appeared with the headline “Warren Endorses Sanders, Breaking With Colleagues.”

The story included quotes attributed to Ms. Warren, Senator Barbara Boxer of California and the actress Lena Dunham, and was published at a URL similar to The Times’s.

“An article circulating on social media tonight that is made to resemble a New York Times story and says Elizabeth Warren endorsed Bernie Sanders is a fake and has no connection to The Times,” said Matthew Purdy, a deputy executive editor of The Times.