How computerized trading exacerbates market volatility, including on a record-setting day

Summary: After several days of major losses, the Dow Jones Industrial saw its largest single-day gain ever, more than 1,000 points, as the markets reopened after Christmas. Since not much has changed in terms of policy, what’s at the root of the volatility? Investment strategist Hugh Johnson joins William Brangham to discuss how the news affects stocks and the “troubling” impact of computerized trading.