Health Net Inc., the medical insurer that has missed analysts’ estimates the past three quarters, said Tuesday that it expects 2013 profit and sales to also fall below expectations. The company’s stock declined in extended trading.

Earnings next year will be $2 a share to $2.10 a share, on revenue of $10.7 billion to $11.2 billion, the Woodland Hills, California-based company said in a statement. Analysts had predicted $2.14 a share in profit and $12.12 billion in revenue on average, according to estimates tracked by Bloomberg.

Health Net shares have fallen 16 percent this year, as financial results suffered from difficulties with processing claims and higher-than-expected medical costs. While premiums should rise faster than costs next year, enrollment will drop by 1 percent to 2 percent as the company pulls away from some markets, Health Net said.

“The company expects commercial enrollment to be more heavily weighted to smaller accounts and tailored network products that have lower than company-average premiums” compared with 2012, Health Net said.

Health Net fell 4.7 percent to $24.46 at 4:31 p.m. New York time after gaining 2 percent during regular trading to close at $25.66.