RenaissanceRe (RNR) reported Q1 operating loss late Wednesday of $1.49 per diluted share, compared with operating income of $12.18 a year earlier.
Analysts polled by FactSet expected a loss of $1.17.
Revenue in the three months ended March 31 rose to $3.47 billion from $2.6 billion a year earlier.
Analysts surveyed by FactSet expected $3.02 billion.