UPDATE 2-Lincoln posts $579 mln 1st-quarter loss

* Lincoln posts Q1 loss of $2.27/share

* Loss driven by $600 mln non-cash goodwill charge

* Operating profit of $0.66/share

* Shares rise 6.3 percent in extended trading (Adds financial detail, background, updates shares)

NEW YORK, May 5 (Reuters) - Lincoln National Corp (LNC.N), one of the largest U.S. life insurers, said on Tuesday it posted a first-quarter loss, hurt by a large goodwill charge related to annuity business.

Philadelphia-based Lincoln said its net loss was $579 million, or $2.27 a share, compared with net earnings of $289 million, or $1.10 a share, in the year-earlier quarter.

The loss included a $600 million non-cash charge related to the impairment of goodwill in Lincoln's annuity business.

The company said it had also changed the features in some variable annuities, a popular retirement product it sells, reducing the risk of future losses.

U.S. life insurers have been weakened by the global financial crisis, hurt by investment losses, as well as higher costs on investment-linked retirement products that guarantee returns.