Countrywide Financial remained the top producer of Alt A MBS as of the midway point in 2006 even though the company gave up a wee bit of market share. Countrywide issued $34.02 billion of Alt A MBS through the first six months of 2006, up 22.2 percent from its production during the same period of 2005, according to the Inside Mortgage Finance MBS Database. But the overall Alt A MBS business was up 27.3 percent… [One data table included]