Will BofA catch Countrywide flu?

Fortune’s Shawn Tully says the $4 billion Bank of America (BAC)-Countrywide (CFC) deal is a smart one, but not everyone agrees. The Service Employees International Union took issue with the deal Friday, urging lawmakers to curb the growth of big banks. The union takes issue with the notion that Countrywide will, as BofA said in its press release Friday, “benefit from the stability of being part of the largest and one of the most financially strong financial institutions in the United States.”

Instead, the union sees the Countrywide deal as increasing the prospect that BofA itself will fail. “Permitting such concentration of risk,” it writes, “would be like putting a sick patient, Bank of America, together in the same room with a highly contagious and terminally-ill patient, Countrywide, and expecting both of them to get better.” If that scenario doesn’t doesn’t strike you as likely, Fortune’s Roddy Boyd offers another: that Countrywide will never again reach its recent profitability levels and faces big writedowns to boot. Regardless, the market seems to like the deal, even given its risks. Maybe investors are just taking BofA chief Ken Lewis at his word. “We are aware,” he said in Friday’s press release, “of the issues within the housing and mortgage industries.” It’s not clear the same was always true of his richly tanned counterpart at Countrywide.