National Interstate ( NATL) rose 6% Wednesday after posting a 29% rise in second-quarter earnings. The Richfield, Ohio-based insurance company earned $9 million, or 47 cents a share, in the quarter, compared with $7 million, or 36 cents a share, a year ago. Analysts surveyed by Thomson First Call were expecting earnings of 44 cents a share in the most recent quarter. Second-quarter revenue rose 14.4% from a year ago to $57.4 million, as against analysts' expectation of $58.2 million. Premium earned increased 12.9% to $52.4 million and net investment income jumped 36.2% to $4.3 million. Losses and loss adjustment expenses increased 9.8% to $30.4 million while losses and loss adjustment expense ratio fell 160 basis points to 58.1%. Underwriting expense ratio decreased 20 basis points to 24.2% and combined ratio stood at 82.3%. The company's stock rose $1.39 to $24.50.