On Monday morning, Mike Wise, a sports columnist at The Washington Post, published to his Twitter account that the Pittsburgh Steelers quarterback Ben Roethlisberger would be suspended for five games.

Now Mr. Wise himself is suspended.

The information Mr. Wise published about Mr. Roethlisberger was made up  a test, he said, of how fast a piece of misinformation could spread online. (Mr. Roethlisberger was suspended for six games, not five, after he was accused of sexual assault in March, and the N.F.L. is considering whether to reduce the suspension.) Mr. Wise followed his initial post about the quarterback with three others about his sourcing for the news. And by the end of the day, the paper had suspended him for a month.

On his radio program on Washington’s WJFK on Tuesday morning, Mr. Wise said, “I could give you 10 reasons why I did this and explain what went wrong in the execution. But none of it matters today. I made a horrendous mistake.”

Kris Coratti, a spokeswoman for The Post, said that she could not comment on personnel issues. Before joining the paper in 2004, Mr. Wise worked as a reporter at The New York Times for 10 years.