Wall Street set for higher open; Yellen in focus

Yellen, who recently signaled that the recovering economy could support a rate hike as soon as June, will speak before the World Affairs Council in Philadelphia at 12:30 p.m. ET. Expectations for the next Fed rate hike were pushed back to at least July after U.S. May non-farm payrolls data on Friday showed employers added only 38,000 jobs in May, far below expectations of 164,000.