There are strains in rich countries, too. Yields on corporate high-yield bonds have jumped from about 6.5% in mid-2015 to 9.7% today. Investors’ aversion spread quickly from energy firms to all borrowers. With bears stalking equity markets, global indices are plumbing 30-month lows (see article). Central bankers in rich countries worry that persistent low inflation will feed expectations of static or falling prices—in effect, raising real interest rates. Policymakers’ ability to respond is constrained because rates, close to zero, cannot be cut much more.