TheStreet.com Ratings provides exclusive stock, ETF and mutual fund ratings and commentary based on award- winning, proprietary tools. Its "safety first" approach to investing aims to reduce risk while seeking total return performance.BOSTON ( TheStreet) -- TheStreet.com's stock-rating model downgraded First Commonwealth Financial ( FCF), a bank in Pennsylvania, to "sell." The numbers: Second-quarter revenue dropped 16% to $80 million as the bank swung to a net loss of $19 million, or 22 cents per share, from a profit of $13 million, or 18 cents per share, in the year-earlier period. The company set aside $42 million for loan losses during the quarter. Its operating and net margins sank into deep negative territory, while its cash decreased 17% to $85 million from a year earlier. The stock: First Commonwealth is down 48% this year, lagging major U.S. indices. The stock offers a lackluster 1.9% dividend yield. The model upgraded casualty and property insurer RLI ( RLI) to "buy." The numbers: Second-quarter revenue declined 10% to $145 million as net income fell 12% to $34 million and earnings per share dropped 11% to $1.57. Its operating margin fell from 34% to 31%, but its net margin remained strong at 24%. RLI has nearly tripled its cash balance to $184 million from the year-earlier quarter. And a debt-to-equity ratio of 0.1 indicates a modest debt load. The stock: RLI has fallen 20% this year, trailing major U.S. indices. The stock trades at an expensive price-to-earnings ratio of 23, but offers a dividend yield of 2.2%. Our model gives RLI a financial strength score of 7.9 out of 10, which is significantly higher than its peers. The model upgraded reinsurer RenaissanceRe Holdings ( RNR) to "buy." The numbers: Second-quarter revenue increased 9% to $507 million as net income surged 93% to $282 million. Earnings per share doubled to $4.32, helped by a lower share count. Its operating margin climbed from 47% to 66% and its net margin expanded from 37% to 55%. The cash cupboard is stocked with $1.3 billion. A debt-to-equity ratio of 0.2 indicates restrained leverage.