Jan. 20 (Bloomberg) -- Cogent Communications Group Inc., the Internet-service provider, fell as much as 23 percent after file-sharing site Megaupload.com was shut down by U.S. authorities as part of a copyright-infringement investigation.

Cogent dropped 14 percent to $16.12 at 10:03 a.m. New York time after declining to $14.50 for the biggest intraday plunge since October 2008. Cogent, based in Washington, is one of the companies that hosted Megaupload.com, Wired.com reported.

To contact the reporter on this story: Alexander Yablon in New York at ayablon@bloomberg.net

To contact the editor responsible for this story: Ville Heiskanen at vheiskanen@bloomberg.net