The Dow and the S&P were slightly lower in late morning trading on Thursday as investors kept a close watch on Hurricane Irma, which was barreling toward Florida. Indexes were also weighed down by a 3.1 percent fall in Walt Disney shares, after the company said its Marvel and Star Wars titles would go exclusively to its planned streaming service. Irma plowed past the Dominican Republic on Thursday after devastating a string of Caribbean islands and killing at least 11 people as one of the most powerful Atlantic storms in a century took aim at Florida.