MetLife , the largest U.S. life insurer, said on Thursday it had a net loss of $1.4 billion, driven by losses on derivatives.

The net loss was equal to $1.74 a share, compared with a profit of $915 million, $1.26 a share, in the year-ago period.

The loss included $1.8 billion in derivatives losses. Derivatives are a type of structured investment tied to the value of underlying assets.

Excluding the losses, MetLife's operating earnings were $723 million, or 88 cents a share, compared with $887 million, or $1.22 a share, in the year-ago period.

Analysts on average expected MetLife to post operating earnings of 68 cents a share, according to Reuters Estimates.

Shares closed up 4 percent at $33.57 on Thursday but were flat in after-hours trade.

(Reporting by Lilla Zuill; Editing Bernard Orr)