Shares of MetLife Inc., the largest U.S. life insurer, fell for a second straight day in New York trading after the company said 2013 operating profit may fall short of analysts’ estimates.

At midafternoon in New York, MetLife was down 2.7 percent at $31.95, the biggest retreat among the 22 companies in the Standard & Poor’s 500 Insurance Index. The New York-based firm has gained 2.4 percent this year.

The insurer said Thursday that profit excluding some investment results may be $4.95 to $5.35 a share next year as low interest rates weigh on returns in its bond portfolio. The average estimate among 19 analysts surveyed by Bloomberg was $5.48 a share before the announcement. The forecast doesn’t include buybacks because MetLife can’t be sure that regulators will allow them.

“Our outlook for MetLife reflects our outlook for no share buybacks in 2013, as well as continued pressure from low interest rates, and a significant presence in variable annuities with tail-risk,” Jay Gelb, an analyst at Barclays Plc, wrote in a research note Thursday. He rates the shares neutral.

Chief Executive Officer Steven Kandarian said Thursday that the insurer can reach 12 percent return on equity by 2016, even if bond yields remain at current levels, near record lows. He’s turning to growth outside the U.S. and expense cuts to boost profit.