The University of Wisconsin-Madison suspended its chapter of Sigma Alpha Epsilon after a member reported multiple instances of racist, anti-Semitic and anti-gay behavior, including one in which he said he was choked and called a racial slur. The fraternity, one of the biggest in the country with about 15,000 members and 200,000 alumni, drew national attention last year after a video of University of Oklahoma chapter members shouting a racist chant on a bus went viral. That was followed by other reports of racism at chapters elsewhere in the country, and a national initiative by the fraternity’s leaders to combat the problem.