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BOSTON ( TheStreet) -- TheStreet.com's stock-rating model upgraded banana seller Chiquita Brands International ( CQB) to "hold."

The numbers: Second-quarter revenue declined 4% to $955 million, but net income increased 46% to $89 million and earnings per share climbed 52% to $1.95. Its gross margin rose from 19% to 22% and its operating margin increased from 7% to 11%. A quick ratio of 1.5 demonstrates ample liquidity. A debt-to-equity ratio of 1 indicates higher-than-ideal leverage.

The stock: Chiquita is up 1% this year, lagging behind major U.S. indices. The company doesn't pay dividends.

The model upgraded industrial machinery maker Chart Industries ( GTLS) to "hold."

The numbers: Second-quarter profit decreased 20% to $18 million, or 61 cents a share, as revenue dropped 22% to $155 million. Its gross margin rose from 34% to 39% and its operating margin jumped from 18% to 22%. The company has a stable financial position, evident in its quick ratio of 1.9 and debt-to-equity ratio of 0.5.

The stock: Chart Industries has surged 79% this year, outpacing major U.S. indices. The stock trades at a price-to-earnings ratio of 7, a discount to machinery stocks and the market. The company doesn't pay dividends.

The model upgraded insurer Mercury General ( MCY) to "hold."

The numbers: Second-quarter net income increased 62% to $114 million, or $2.07 a share, as revenue grew 1% to $796 million. Its gross margin rose from 13% to 22% and its operating margin jumped from 12% to 20%. The company has a strong financial position, with $290 million of cash, compared to $273 million of debt.

The stock: Mercury General has fallen 21% this year, trailing major U.S. indices. The stock pays a 6.4% dividend yield, higher than the S&P 500 average of 3.6%. The company posted losses in the third and fourth-quarter of 2008.

The model upgraded McGrath RentCorp ( MGRC), which rents out test equipment and modular buildings for classrooms and office space, to "buy."

The numbers: Second-quarter profit dropped 30% to $7 million, or 30 cents a share, as revenue declined 10% to $66 million. Its gross margin increased from 65% to 67%, but its operating margin dropped from 26% to 20%. The company has weak liquidity, with just $450,000 of cash. A debt-to-equity ratio of 1 indicates higher-than-ideal leverage.

The stock: McGrath has declined 9% this year, underperforming major U.S. indices. The stock trades at a price-to-earnings ratio of 13, a discount to support-service peers and the market. The shares offer a 4.5% dividend yield.

The model downgraded oil and gas producer Marathon Oil ( MRO) to "hold."

The numbers: Second-quarter net income decreased 47% to $413 million and earnings per share dropped 55% to 48 cents. Revenue fell 42% to $12 billion. Its gross margin rose from 11% to 16% and its operating margin climbed from 6% to 7%. A quick ratio of 0.7 indicates weak liquidity. A debt-to-equity ratio of 0.4 demonstrates conservative leverage.

The stock: Marathon Oil is up 12% this year, in line with the S&P 500 Index. The stock trades at a price-to-earnings ratio of 8, a discount to integrated oil and gas peers and the market. The shares offer a 3.1% dividend yield.

-- Reported by Jake Lynch in Boston.

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