Goldman Sachs is getting into jails, but not in the way some Americans would like. Utilizing a social-service bond—a new financial instrument—the most notorious investment bank will put $10 million into a program to cut the recidivism rate at New York City’s Rikers Island prison. The bond will be backed by a guarantee from Bloomberg Philanthropies, New York Mayor Michael Bloomberg’s philanthropic arm. For Goldman to get its money back on the deal, recidivism at the prison has to drop by at least 10 percent. If it falls lower than that, Goldman could make $2.1 million on its investment.